Inference_Practice_Questions_and_Solutions.pdf

Inference

Practice Questions & Solutions

Authored by: e-GMAT CR Team

e-GMAT LLC. Unauthorized copying for commercial or competitive purposes is not allowed.

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TABLE OF CONTENTS

INTRODUCTION ............................................................................................................................................................................ 2

QUESTIONS FOR PRACTI CE - INFERENCE ....................................................................................................... 3

OG 13 QUESTION NO.91 ............................................................................................................................................... 4

OG 13 QUESTION NO.103 ........................................................................................................................................... 7

OG 13 QUESTION NO.104 ........................................................................................................................................ 10

OG 13 QUESTION NO.105 ........................................................................................................................................ 13

VERBAL REVIEW 2 N D ED. QUESTION NO.64 ............................................................................................ 15

VERBAL REVIEW 2 N D ED. QUESTION NO.75 ............................................................................................ 17

GMAT PREP MAGAZINE SUBSCRIBERS ........................................................................................................ 19

GMAT PREP PXC HOME COMPUTERS ............................................................................................................ 21

GMAT PREP COMCORP SHIPPING CLE RK .................................................................................................. 23

GMAT PREP PARASITIC WASPS ......................................................................................................................... 26


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INTRODUCTION

Dear Students,

We hope that your preparation is proceeding smoothly.

After completing the Inference concept and application files, please be sure to practice the official questions as recommended in this document. Ensure that you apply the process to solve these questions.

Secondly, the CR team at e-GMAT is glad to share with you that we now provide detailed solutions to the most challenging questions in OG13 (Q90-123), VR 2nd Edition (Q60-83) and GMAT Prep Software (New and Old).

We are proud to share these solutions with you and hope that these solutions contribute to your success in GMAT.

So in this document you will find the following:

1. List of practice questions from Official Guides that you should attempt. 2. Solutions of the most challenging Inference questions in official sources. Please note that

these solutions do not cover all the questions part of the list in point 1 above.

Well wait eagerly for feedback for these solutions (appreciative as well as critical) from your side.

Regards,

Chiranjeev Singh

PS: Please note that because of copyright issues, we cannot copy paste complete question text for OG13 and VR 2nd Edition questions.


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QUESTIONS FOR PRACTICE

OG13: 26, 38, 54, 55, 60, 66, 91, 103, 104, 105 Verbal Review 2nd Edition: 12, 14, 19, 43, 53, 57, 64, 75


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OG 13 QUESTION NO.91

Environmentalist: The commissioner of the Fish and Game Authority The environmentalist's statements, if true, best support which of the following as a conclusion? (A) The use of technology is the... (B) It is possible to . (C) The proportion of marine fish .... (D) Modern technologies ... (E) Marine fish continue .

SOLUTION

PASSAGE ANALYSIS

Environmentalist: The commissioner of the Fish and Game Authority is no longer endangered.

Key-points from this statement: (1) Environmentalist--author of the

argument (2) Environmentalist comments on a claim

made by a certain authority (3) Claim by the authority- increase in the

number of marine fish caught= marine fish not endangered

This is a specious a lack of danger to that resource.

Key-points from this statement: (1) Environmentalist calls the above claim

false (conclusion of the argument) (2) Gives an analogy to prove his/her point (3) Analogy- just as it would be absurd to

deduce that the rain forest is not in danger because the number of trees being cut show how abundant it is, it would be illogical to say that the marine fish are not in danger since there have been increases in its catch.

The real cause that deplete resources. Key-points from this statement:

(1) Author cites increased efficiency in the use of technology as the real cause for the increase in the fish-catch

(2) Blames technology for depleting resources in this situation

PRE-THINKING


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In this question, we need to find the conclusion of the passage. The conclusion has to come on the

basis of the given statements. In order to arrive at a possible conclusion choice, lets examine the

argument carefully.

From our passage analysis, we know that the environmentalist thinks that the claim made by a

certain authority is false. Now the authoritys claim is that:

increase in the number of marine fish caught = marine fish not endangered anymore

The author then holds the use of certain technologies responsible for having caused these increases

in the fish catch and accuses it for depleting resources in this case. Since the author makes this

accusation against the use of certain technologies, we can infer that the author thinks that:

(1) The use of some technologies sometimes interferes with safeguarding natural resources.

Also, since the author says that the increase in the catch of the marinefish does not mean that the

marinefish is not endangered, the author thinks that the marinefish continues to be exploited and

hence its status has not improved. If it was endangered before, it definitely is still endangered. .

Therefore, we can conclude that:

(2) The status of the marine fish is still endangered.

With these pre-thought answers, lets evaluate the answer choices.

ANALYSIS OF OPTION STATEMENTS

A. The use of technology is the...

This option is incorrect. It over-generalizes the crux of environmentalists argument. The environmentalist does say that the increases in the fish-catch are due to the use of such technologies that deplete resources; however, on the basis of this statement, one cannot infer that this is always the case with the use of technology. In our pre-thinking we considered an option that could be mistaken for being on similar lines. BUT our option was limited to the scope of this argument. We said that : The use of some technologies sometimes interferes with safeguarding natural resources. This is different from saying that the use of technologies is always responsible for unjustifiably exploiting nature. Hence, as is, this answer choice is not the correct answer.

B. It is possible to .

This option is incorrect. It is out of scope. The environmentalist never talks of using other sources for measuring the number of fish in the sea. In fact, he/she never even indicates in that


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direction. The discussion of the argument is limited to how determining the number/abundance of fish from its catches is illogical.

C. The proportion of marine fish ....

This option is incorrect. It takes certain words from the argument but completely changes the context in which they have been used. The author/environmentalist gives the analogy of the rain forest to establish a point. His/her point is that just as it would be absurd to deduce that the rain forest is not in danger because the number of trees being cut show how abundant it is, it would be illogical to say that the marine fish are not in danger since there have been increases in its catch. The environmentalist by no means has compared--explicitly or implicitly, the respective proportions of cut tree with the caught fish.

D. Modern technologies ...

This option is incorrect. It is out of scope. The author of the argument never touches on the edibility/usability aspect of the fish.

E. Marine fish continue . This is the correct option. It is exactly on the lines of our pre-thought answer. In the argument, the environmentalist disputes the claim that the increases in the number of marinefish caught prove that these fish are not endangered anymore. In fact, the author thinks that the increases in the fish-catch represent a depletion of the resource. Therefore, one can safely conclude that the marine fish continue to be endangered.


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For a trade embargo against over the embargo. The claims above, if true, most strongly support which of the following conclusions? (A) The balance of opinion ... (B) As long as international ... (C) A naval blockade ... (D) Any trade embargo ... (E) For a blockade of ...

SOLUTION

PASSAGE ANALYSIS

For a trade embargo country must be sustained.

In this statement, the author presents two pre-conditions under which a trade barrier against a country is successful. These conditions are:

(1) Great degree of international agreement (2) Ability to execute the barrier: stopping

the entry and exit of goods from the country against on which the barrier has been imposed.

A total blockade over the embargo. In this statement the author presents a consideration. The author brings up the likelihood of an international disagreement over blocking a particular countrys (Patrias) ports to make the trade barrier against it a success.

PRE-THINKING

Please note that the passage ends at the statement that that blocking Patrias ports is likely to lead to an international disagreement. Now since the question stem asks us to conclude for the given passage, we must take into account every piece of information given in it and frame a choice that does not require any outside information. So lets get cracking.

So far we know that:

(1) Two necessary conditions for the success of a trade barrier: a. Great degree of international agreement b. Ability to execute the barrier

(2) Executing trade barrier on Patria is likely to lead to international disagreement Now what can we possibly conclude from the given statements?


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We know chances are that one necessary condition for the trade barrier against Patria to become success may not be fulfilled. Hence we can conclude that:

A trade embargo against Patria is not likely to be successful. Please note that since the author doesnt concretely say that there will be a disagreement over the execution of the trade barrier, in our conclusion we cannot use a definitive word such as will.

With this understanding, lets screen the answer choices.


A. The balance of opinion ...

This option is incorrect. From the passage, we only that there will be disagreement over blockade. So, it means that at least one country will be against the blockade. However, balance of opinion means majority. We cannot conclude that majority of countries will support Patria.

B. As long as international ....

This option too is incorrect. In our passage analysis we clearly saw that for a trade barrier to succeed we need two pre-requisites. This choice says that one of them, namely international agreement, is enough. But what about the other condition? What about the execution of the barrier? Since this choice walks against the premise of the argument, this cannot be the correct choice.

C. A naval blockade ...

This option is incorrect. This choice merely provides us with some extra information about how the trade barrier will be executed in Patrias case (through naval blocade) or the purpose behind blocking its ports ( to ensure that no goods enter or leave Patria) . If you notice the logical progression of the argument carefully, the author has already explicitly moved past the point of discussing the how and why aspect of the blockade of the ports. Towards the end of the argument, the author is concerned with the impact of the blockade. Since the correct conclusion choice will carry forward from this point, we can see that this answer choice is not a good fit for the same. Hence answer choice C is not correct.

D. Any trade embargo ...

This option is correct. This is in line with our pre-thinking. Please note the mild language of this answer choice: would be likely to fail at some time. The language of this choice is in keeping with the stated opinion of the author:


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such an action would be likely to cause international discord over the embargo Both the last statement and the answer choice, do not concretely state the predictions made. This clearly shows that answer choice D factors in the last statement and does not require any extra assumptions to be true; it follows the logical progression of the argument. Hence, this is the correct answer choice.

E. For a blockade of ...

This answer-choice is incorrect for two reasons:

(a) if you read carefully, this choice talks about the success of the blockade of Patrias ports. However, the argument gives us no information regarding the same. The only information given to us is about the necessary pre-conditions of the success of a trade embargo and an implication of blocking Patrias ports. So, this statement cannot be concluded.

(b) Even if we put aside the distinction made above about the two different kinds of successes, we can see that the stated conclusion in this choice is not justified. Reason: As per one of the pre-conditions for the success of a trade embargo/barrier, there needs to be a high/greater than normal degree of international agreement. So it is NOT necessary that the international opinion has to be unanimous. A high degree would suffice.

Hence answer choice E is not the correct answer. .


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Theater Critic: The play La Finestrina, .. The considerations given best serve as part of an argument that A. modern audiences would find B. Groucho Marx once performed C. in the United States D. the performance of the E. the director of La

SOLUTION

PASSAGE ANALYSIS

The play La Finestrina, . in a modern theater. Key points from these two statements: (1) Some play that is now performed at

Central Theater was written in Italy in the eighteenth century

(2) The director of this play opines that the current presentation of the play is as close to the original presentation as possible in a modern theater.

Although the actor in sixteenth-century Italy. Key- points from this statement: (1) An actor from the current presentation

of the play essays his role in the play like a particular comedian from the twentieth century.

(2) The acting style of the comedian (from the twentieth century) was within an acting tradition that began in Italy in the sixteenth century.

PRE-THINKING

Please note that the above statements do not form an argument. As of now they are a part of fact set. When we read the question-stem, we realize that we need to form an argument with the given statements. In order to do so, we need to find the correct conclusion. Hence, essentially the question stem asks us to look for a conclusion in the answer choices. So lets get cracking.

The statements are loaded with information. Lets try to simplify the presentation of the facts:

(1) A play was written in Italy in the eighteenth century (2) That play is now performed at a theater


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(3) The current productions director says that his presentation of the play is as close to the original as possible in a modern theater

(3) The author states that an actor in the current presentation essays his role in the play like a particular comedian from the twentieth century.

(4) The acting style of the comedian from the twentieth century was within an acting tradition that began in sixteenth century Italy.

So far the statements presented look like loose pieces of information. So the onus will be on the conclusion to tie them up together. The common thread between the directors claim and the authors opinion is that the actor in the current presentation of the play acts according to an acting tradition that dates back to an era which is possibly closer to when the play was originally written than the modern time.

With this understanding, lets screen the answer choices.


A. modern audiences would find

This option is incorrect. It is completely out of scope. The preference or the likes and dislikes of the audiences have not been mentioned in the argument. Since a conclusion has to naturally flow from the given premises, this option choice is not correct.

B. Groucho Marx once performed

This option too is incorrect. It is not based on any of the premises given in the argument. The passage neither explicitly nor implicitly supports this statement. Hence, this answer choice is incorrect.

C. in the United States

This option is incorrect. It is out of scope. We know nothing about the training of actors in the twentieth century. All we know from the passage is that the acting style of one of the actors of the twentieth century (the comedian) fell inside an acting tradition that began in sixteenth century Italy. On the basis of this information, we certainly cant draw a generalized conclusion about the training of actors in the twentieth century.

D. the performance of the

This option is correct. This choice matches our understanding of and relation between the premises given in the argument. If the acting style of an actor in the current presentation of the play dates back to an era that was closer to when the play was originally written, then certainly this fact does not go against the directors claim that the play is as close to its original version as possible in modern theater. Moreover, please note the safe language used in the correct answer choice:


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does not serve as evidence against the director's claim The correct conclusion choice does not say that the resemblance in the acting style of the actor who plays Harlequin in La Finestrina proves that the directors claim is valid. It just says that this resemblance is not in the opposite direction as the directors claim. Also, this option choice perfectly ties up the loose pieces of information given to us in the argument. Hence, this is the correct answer choice.

E. the director of La

This answer-choice is incorrect. It picks up words from the argument but changes the context just enough to make it incorrect. The author has given us no information to support that the director must have advised the actor on his acting style. Also, please note that this answer choice uses very strong language: the director of La Finestrina must have advised Unless explicitly mentioned or indicated in the passage, using such strong words in the conclusion cannot be justified. Hence, this is not the correct choice.


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The cost of producing radios produce radios in Country Y. The statements above, if true, best support which of the following assertions? A. Labor costs in Country ... B. Importing radios from Country ... C. The tariff on a ... D. The fee for transporting ... E. It takes 10 percent ...

SOLUTION

PASSAGE ANALYSIS

The cost of producing in Country Y. Key-points from this statement: 1. There are two countries: Country Q and Country Y 2. Cost of producing radios in country Q is

10% less than that in country Y Even after transportation in Country Y. According to this statement, it is cheaper to

import radios from country Q to country Y even after adding the following two costs: a) transportation fees and b) tariff charges

PRE-THINKING

The question stem asks us to identify one statement from the answer choice that will hold true purely based on the information given in the passage. Given the passage analysis, one possible answer should jump right at you.

Lets look at the facts again:

1. Cost of producing radios in country Q is 10% less than that in country Y 2. It is cheaper to import radios from country Q to country Y even after adding the following

two costs: a) transportation fees and b) tariff charges

So, essentially the author is trying to say that the total cost of the two charges is not equal to the difference in the cost of producing radios between the two countries. Since the difference in the cost of producing radios is that the cost of producing radios in country Q is 10% less than that in country Y, we can definitely infer that

The total cost of the transportation fee and the tariff charges, levied while importing radios from country Q to country Y, is less than 10% of the cost of producing radios in country Y.

Keeping the above inference in mind, lets evaluate the answer choice given below.


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A. Labor costs in Country

This option is incorrect. The correct inference has to come out of the information given in the passage. Since labor costs have not been mentioned in the passage, no inference can be made about the same. Therefore, answer choice A is not correct.

B. Importing radios from Country

This option is not correct. It too, like answer choice A, is out of scope. Since no other implication, except for monetary cost of importing, has been given regarding the import of radios from Country Q to Country Y, we cannot infer anything about the elimination of jobs in country Y.

C. The tariff on a

This is the correct answer. It is a subset of the inference choice that we thought of in the pre-thinking phase. As proved then, since the total cost of the transportation fee and the tariff charges levied while importing radios, is less than 10% of the cost of producing radios in country Y, we can definitely infer that any of the these two charges are less than 10 percent of the cost of manufacturing the radio in Country Y. Therefore, answer choice C is correct.

D. The fee for transporting

This answer choice is incorrect. We cannot deduce the information given in answer choice D. This is because the information given in the passage only gives us the upper limit of the two charges but does not give us any lower limit of each of the two charges involved while importing the radios from Country Q to Country Y. Hence, answer choice D is not correct.

E. It takes 10 percent ...

This answer choice is incorrect. No information has been given regarding the time taken to manufacture the radios in either of the two countries. Hence, we cannot deduce anything about this element. Therefore, answer choice E is beyond the scope of the argument.


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VERBAL REVIEW 2 N D ED. QUESTION NO.64

High levels of fertilizer... To receive governmental ... The statements above, if true, best support which of the following conclusions?

A. The rules for governmental B. The only solution to ... C. Farmers can continue to ... D. New farming techniques will ... E. Governmental price supports for ...

SOLUTION

PASSAGE ANALYSIS

High levels of , pollute water supplies. In the first sentence of the passage we come to know that when farmers try to produce high yield of the same crop year after year, they need high levels of fertilizers and pesticides to do so. However, such a practice pollutes water supplies.

Experts therefore plantings yearly. We are then told that to avoid the above situation, experts advise and encourage farmers to change their crops and rotate their plantings yearly.

To receive governmental past several years. From this final piece of information, we come to know that in order to receive price support benefits from the government, farmers need to fulfill a criterion. The criterion is that they must have produced the same crop (for which they want to receive the benefit) for the past several years.

PRE-THINKING

If you read the passage carefully, you will notice that there is no given conclusion. The passage just provides several pieces of information. Our task in this question is to figure out one statement that can be concluded from this information set. In order to do so, lets revisit the given information once more:

1. Farmers indulge in heavy use of pesticides and fertilizers, which leads to water pollution


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2. Reason for above: they want to get more productivity from the same land and for the same crop

3. Experts advise crop rotation to avoid water pollution 4. Governments price support policy only benefits those farmers who have grown the

same crop for several years Now, if you notice, statement number 3 and 4 above go in the opposite direction. Whereas on the one side, experts urge farmers to diversify their crops in order to reduce water pollution, on the other the governments policy encourages farmers to keep growing the same crop year after year. Growing the same crop over several consecutive years, as we are told, contributes to water pollution. From this analysis, we can clearly see that the governments rule for availing price-benefits is incompatible with the experts advice. Accordingly, we can conclude that:

The governments price-support benefits discourage farmers to adopt the suggested measures for reducing water pollution.

With the above analysis in mind, lets move on to evaluating the given answer choices.


A. The rules for governmental

This is the correct answer and it almost matches the statement we came up with in the pre-thinking phase. As explained above, if farmers are discouraged to adopt crop diversification and plant rotation- - a measure directed at reducing water pollution- because of the governmental policy, we can conclude choice A.

B. The only solution to ...

Option B is incorrect as it suggests something that is not at all supported by the information given in the passage. The only solution mentioned in the passage is of crop diversification and plant rotation. Clearly, we cannot conclude anything about ceasing farming from the passage.

C. Farmers can continue to

This is not correct choice. Since the passage does not talk at all about the profit made by farmers, we cannot conclude choice C.

D. New farming techniques will ...

This is not the correct answer. We cannot comment on what will or will not happen in the given situation. Our task in this question is to conclude something that can be derived purely on the basis of the given information. Since there is no talk about future measures, we cannot conclude choice D.

E. Governmental price supports for ...

This choice too, like all the other incorrect choices, talks an element that is never mentioned in the given passage. Since no information has been given about the levels of price-support and their effect on debt of farmers (if any), we cannot conclude choice E.


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VERBAL REVIEW 2N D ED. QUESTION NO.75

United States hospitals have traditionally at or below actual costs. Which of the following conclusions is best supported by the information above? A. Although the advance of ... B. If hospitals do not ... C. Some patients have incomes ... D. If the hospitals reduce ... E. Even though philanthropic donations ...

SOLUTION

PASSAGE ANALYSIS

United States hospitals unreimbursed care. In the first statement we get to know that hospitals in the US have traditionally relied mostly on revenues from paying patients to make up for the losses incurred from unreimbursed care.

Almost all paying hospital bills. Here we are told that in the current scenario, almost all paying patients rely on either governmental or private health insurance to pay their hospital bills.

Recently, insurers have .. actual costs. In the final statement, we are told that off lately insurers have been very strict in reimbursing hospitals for the care availed by the insured patients. The insurers have been limiting the reimbursements to the hospitals to amounts at or below actual costs.

PRE-THINKING

The accompanying question stem asks us to find a conclusion that is best supported by the given passage. Lets revisit the information given in the passage to extract the maximum out of it. We are told that:

1. two kinds of patients in US hospitals: paying and non-paying 2. US hospitals have traditionally relied on paying patients to make up for the losses for non-

paying ones 3. Now, almost all paying patients have some sort of insurance 4. Insurers are now strict with reimbursements: pay hospitals at or below actual costs

If you notice, point number 3 and 4 above do not go in favor of point 2. This is because if insurers reimburse hospitals at or below the actual costs borne by them for paying patients, then the hospitals will have difficulty extracting extra money out of these patients. Under such


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circumstances, the hospitals will not be able to rely on paying patients to offset the losses borne from unreimbursed care. Accordingly, we can conclude that:

If US hospitals carry on with providing unreimbursed care, they must find other sources to finance it.

With the above pre-thinking in mind, lets evaluate the given answer choices.


A. Although the advance of ...

This choice is incorrect. It talks about advance of technology, and access to expensive medical procedures by patients with varied financial resources. As the passage doesnt give us any information regarding these topics, we cannot conclude anything regarding them.

B. If hospitals do not ...

This is the correct answer. It is very close to the conclusion we came up with in the prethinking phase. As the US hospitals will not be able to finance the unreimbursed care from their primary source- paying patients, due to the stricter attitude of insurers regarding reimbursements, they will have to look for other sources of income to do so. If they cant find alternate sources but still choose to carry on with providing such care, then will naturally suffer losses.

C. Some patients have incomes ...

This is not the correct answer. In the passage, we are not given any information regarding why some patients may not have any form of insurance. Infact there is no mention of patients incomes, affordability of private insurance or eligibility for governmental insurance. Clearly, we cant conclude choice C from the given passage.

D. If the hospitals reduce

This is not the correct answer. The passage clearly states that the insurers now strictly reimburse hospitals at or below actual costs. So even if hospitals reduce their costs, the insurers will still settle the hospital bills at or below those reduced costs. Hence, there will be no extra funds for reimbursed care from paying patients.

E. Even though philanthropic donations

This is not the correct answer. Choice E is not at all supported by the passage. The passage provides no information on either philanthropic donations or their support to hospitals.


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GMAT PREP MAGAZINE SUBSCRIBERS

Finding of a survey of Systems magazine subscribers: Thirty percent of all merchandise orders placed by subscribers in response to advertisements in the magazine last year were placed by subscribers under age thirty-five.

Finding of a survey of advertisers in Systems magazine: Most of the merchandise orders placed in response to advertisements in Systems last year were placed by people under age thirty-five.

For both of the findings to be accurate, which of the following must be true?

A. More subscribers to Systems who have never ordered merchandise in response to advertisements in the magazine are age thirty-five or over than are under age thirty-five.

B. Among subscribers to Systems, the proportion who are under age thirty-five was considerably lower last year than it is now.

C. Most merchandise orders placed in response to advertisements in Systems last year were placed by Systems subscribers over age thirty-five.

D. Last year, the average dollar amount of merchandise orders placed was less for subscribers under age thirty-five than for those aged thirty-five or over.

E. Last year many people who placed orders for merchandise in response to advertisements in Systems were not subscribers to the magazine.

SOLUTION

PASSAGE ANALYSIS

Finding of a survey of Systems magazine subscribers: Thirty percent of all merchandise orders placed by subscribers in response to advertisements in the magazine last year were placed by subscribers under age thirty-five

Orders by Subscribers under age 35 = 30% of (All merchandise orders by subscribers)

Finding of a survey of advertisers in Systems magazine: Most of the merchandise orders placed in response to advertisements in Systems last year were placed by people under age thirty-five.

Orders by People under age 35 = Majority of merchandise orders Most or Majority means over 50 percent.

PRE-THINKING

For both of the findings to be accurate, which of the following must be true?

This is an inference question. For both findings to be accurate, what else must be true?

The first finding is from a survey of subscribers to the magazine, while the second is from a survey of advertisers. The first tells us that subscribers under 35 placed 30 percent of orders placed by


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subscribers, while the second tells us that people under 35 placed most of the orders placed as a whole, and not just by the magazines subscribers.

Now, we see that subscribers under 35 can at most account for only 30% of the orders. Given that people under 35 accounted for majority of the order, we can infer that more than 20% of the orders were placed by non-subscribers under age 35.


A. More subscribers to Systems who have never ordered merchandise in response to advertisements in the magazine are age thirty-five or over than are under age thirty-five.

This choice refers to subscribers who have never ordered merchandise. Since we are looking for an inference about people under 35 who have ordered merchandise, this choice cannot be the correct one.

B. Among subscribers to Systems, the proportion who are under age thirty-five was considerably lower last year than it is now.

We cannot infer anything about the proportion of subscribers under age 35 based on information about the orders placed by those under 35. We do not have any relationship between the number of subscribers and the number of orders placed by them.

C. Most merchandise orders placed in response to advertisements in Systems last year were placed by Systems subscribers over age thirty-five.

From the survey of the advertisers, we know that most orders were by people under 35. This means that fewer than 50% of the total orders were by people over age 35. Therefore, this option is actually against the information in the passage and is therefore incorrect.

D. Last year, the average dollar amount of merchandise orders placed was less for subscribers under age thirty-five than for those aged thirty-five or over.

Since the passage does not mention the dollar amount of merchandise for orders placed, we cannot infer anything about it from the given information.

E. Last year many people who placed orders for merchandise in response to advertisements in Systems were not subscribers to the magazine.

This choice is in line with our prethinking. It must be true for both the given findings to be correct, since it states that many people who placed orders were not subscribers. This explains how most of the total number of orders placed was by people under 35, even though subscribers under 35 constituted only 30 percent of all merchandise ordered by subscribers.


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GMAT PREP PXC HOME COMPUTERS

First-time computer buyers buying PXC home computers typically buy models that cost much less and have a smaller profit margin per computer than do PXC computers bought by people replacing their computers with more powerful models. Last year PXC's profits from computer sales were substantially higher than the previous year, although about the same number of PXC computers were sold and the prices and profit margins for each computer model that PXC sells remained unchanged.

If the statements above are true, which of the following is most strongly supported by them?

A. PXC's competitors raised the prices on their computers last year, making PXC computers more attractive to first-time computer buyers.

B. The number of people buying PXC computers who also bought PXC computer-related products, such as printers, was larger last year than the previous year.

C. Among computer buyers who bought a PXC computer to replace their existing computer, the proportion who were replacing a computer made by a competitor of PXC was greater last year than the previous year.

D. The proportion of PXC computers bought by first-time computer buyers was smaller last year than the previous year.

E. PXC's production costs for its computers were lower last year than they had been the previous year.

SOLUTION

PASSAGE ANALYSIS

First-time computer buyers buying PXC home computers typically buy models that cost much less and have a smaller profit margin per computer than do PXC computers bought by people replacing their computers with more powerful models.

This statement gives us two facts about first-time computer buyers who buy PXC home computers. They typically buy models that (1) cost much less and (2) have a smaller profit margin than do PXC computers bought by people replacing their computers.

Last year PXC's profits from computer sales were substantially higher than the previous year, although about the same number of PXC computers were sold and the prices and profit margins for each computer model that PXC sells remained unchanged.

This statement tells us that PXCs profits from sales last year were substantially higher than the previous year, despite the fact that PXC sold about the same number of computers and the profit margins for its models did not change.

PRE-THINKING

If the statements above are true, which of the following is most strongly supported by them?

The question stem asks us to identify an inference that can be derived from the given information. One of the key things to remember about such questions is that it is important to stay within the


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scope of the information given in the passage. We cannot find a supporting statement that is about something other than the information given in the passage.

What do we know from the passage?

1. First-time computer buyers who buy PXC computers usually buy models that cost much less and have smaller profit margins than the PXC models bought by people replacing their computers.

2. PXCs profits from computer sales went up significantly last year, even though it sold about the same number of computers and its profit margins were unchanged.

What can we infer from this information? The first statement tells us that a PXC customer replacing a computer is typically more likely to buy a more costly computer with a higher profit margin than a PXC customer buying a computer for the first time. So, PXCs profits could have gone up despite no change in the profit margins and the approximate number of computers sold if a greater proportion of computers were bought by people replacing their computers rather than by first-time buyers.


A. PXC's competitors raised the prices on their computers last year, making PXC computers more attractive to first-time computer buyers.

The passage does not give us any information about PXCs competitors, so we cannot derive any inference about them. Therefore, this option is incorrect.

B. The number of people buying PXC computers who also bought PXC computer-related products, such as printers, was larger last year than the previous year.

The passage refers only to PXCs profits from computer sales. Information about sales of computer-related products is outside the scope of the passage.

C. Among computer buyers who bought a PXC computer to replace their existing computer, the proportion who were replacing a computer made by a competitor of PXC was greater last year than the previous year.

It is irrelevant which model the computer buyers were replacing. Customers replacing their computers are relevant to this context only in terms of the information that they are typically more likely to buy more costly PXC models with higher profit margins than the models bought by first-time buyers. This statement cannot be derived from the passage.

D. The proportion of PXC computers bought by first-time computer buyers was smaller last year than the previous year.

This option is in line with our prethinking. If the given statements are true and PXCs profits from computer sales went up even though its computer sales and profit margins remained constant, then it stands to reason that a greater proportion of its customers were replacing their computers rather than buying computers for the first time.

E. PXC's production costs for its computers were lower last year than they had been the previous year.

The passage says that the profit margins for both kinds of computers have remained unchanged. Therefore, this option statement actually runs counter to the given information.


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GMAT PREP COMCORP SHIPPING CLERK

Comcorp Shipping Clerk: Last week, no shipments of building supplies were sent out on Friday. The five specially ordered shipments sent out last week were sent out on Thursday, and each of those specially ordered shipments consisted entirely of building supplies. Four shipments were sent to Truax Construction last week, none of which consisted of building supplies.

If the shipping clerk's statements are true, which of the following must also be true?

A. All of Comcorp's shipments of building supplies last week were specially ordered. B. None of Comcorp's shipments sent on Friday of last week was sent to Truax Construction. C. None of the shipments sent by Comcorp by Truax Construction last week was specially ordered. D. None of Comcorp's shipments sent on Thursday of last week was sent to Truax Construction. E. All of Comcorp's shipments of building supplies last week were sent out on Thursday.

SOLUTION

PASSAGE ANALYSIS

Comcorp Shipping Clerk: Last week, no shipments of building supplies were sent out on Friday.

This statement tells us that Comcorp did not send out any shipments of building supplies on Friday last week. So, it could have sent out shipments of other supplies on Fridaybut none of the Friday shipments consisted of building supplies.

The five specially ordered shipments sent out last week were sent out on Thursday, and each of those specially ordered shipments consisted entirely of building supplies.

This statement tells us that there were only five shipments sent out last week that were specially ordered. The use of the before five specially ordered shipments tells us that there were no more than five specially ordered shipments sent last week. These five shipments were all of building supplies and were all sent on Thursday.

Four shipments were sent to Truax Construction last week, none of which consisted of building supplies.

This part tells us that Comcorp sent four shipments to its customer, Truax Construction, last week. None of Truaxs shipments consisted of building supplies.

PRE-THINKING

If the shipping clerk's statements are true, which of the following must also be true?

The question stem asks us to identify a statement that can be inferred from the given information.

First, lets identify all the information given in the passage about shipments sent by Comcorp last week.


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1. No building supplies were sent on Friday. 2. All five specially ordered shipments were sent on Thursday, and all five consisted only of

building supplies. 3. Four shipments were sent to Truax, and none of these consisted of building supplies.

What can we derive from this information? First, from (2), we can infer that there were no special orders sent out last week for shipments other than building supplies. We can also infer from this statement that there were no specially ordered shipments sent on any day last week other than Thursday.

Also, from the information given about Truax, we can infer that no specially ordered shipment was sent to Truax last week, since none of its shipments consisted of building supplies, and all the specially ordered shipments consisted of building supplies.


A. All of Comcorp's shipments of building supplies last week were specially ordered.

This option is incorrect. The passage says that all five specially ordered shipments sent last week consisted of building supplies. This does not mean that only five shipments of building supplies were sent last week. Other shipments of building supplies that were not specially ordered could have been sent last week.

B. None of Comcorp's shipments sent on Friday of last week was sent to Truax Construction.

This option is incorrect. The only information given in the passage about Friday is that none of Fridays shipments consisted of building supplies. Since none of the shipments sent to Truax last week consisted of building supplies, one or more of other shipments could have been sent to Truax on Friday.

C. None of the shipments sent by Comcorp by Truax Construction last week was specially ordered.

We know from the passage that all five specially ordered shipments sent last week were for building supplies. Since none of the four orders sent to Truax consisted of building supplies, it can correctly be derived from the passage that none of the specially ordered shipments was sent to Truax. This is the correct answer.

D. None of Comcorp's shipments sent on Thursday of last week was sent to Truax Construction.

This option is incorrect. The passage does not tell us how many shipments were sent on Thursday. All five specially ordered shipments, which consisted of building supplies, were sent on Thursday. But there could also have been other shipments sent on Thursday that were not specially ordered, and one or more of these could have been sent to Truax.

E. All of Comcorp's shipments of building supplies last week were sent out on

This option is incorrect. We know from the passage that all five specially ordered shipments


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Thursday. sent last week were sent on Thursday, and that all of these five shipments consisted of building supplies. This does not mean that only five shipments of building supplies were sent on Thursday. Other shipments of building supplies that were not specially ordered could have been sent on Thursday.


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GMAT PREP PARASITIC WASPS

Parasitic wasps lay their eggs directly into the eggs of various host insects in exactly the right numbers for any suitable size of host egg. If they laid too many eggs in a host egg, the developing wasp larvae would compete with each other to the death for nutrients and space. If too few eggs were laid, portions of the host egg would decay, killing the wasp larvae.

Which of the following conclusions can properly be drawn from the information above?

A. The size of the smallest host egg that a wasp could theoretically parasitize can be determined from the wasp's egg-laying behavior.

B. Host insects lack any effective defenses against the form of predation practiced by parasitic wasps.

C. Parasitic wasps learn from experience how many eggs to lay into the eggs of different host species.

D. Failure to lay enough eggs would lead to the death of the developing wasp larvae more quickly than would laying too many eggs.

E. Parasitic wasps use visual clues to calculate the size of a host egg.

SOLUTION

PASSAGE ANALYSIS

Parasitic wasps lay their eggs directly into the eggs of various host insects in exactly the right numbers for any suitable size of host egg.

This statement tells us about the way in which parasitic wasps lay eggs. They lay their eggs directly into the eggs of host insects. The wasp eggs are laid in exactly the right numbers for any suitable size of host eggs. Note that suitable modifies the size of the host eggs, not the number of wasp eggs that are laid inside the host egg. When the size of the host egg is suitable, the wasp lays exactly the right number of eggs inside the host egg.

If they laid too many eggs in a host egg, the developing wasp larvae would compete with each other to the death for nutrients and space.

This statement tells us that the eggs laid by the parasitic wasp into a host insects eggs cannot be too many in number. This part corresponds to the last part of the previous statement, which says that the wasp lays exactly the right number of eggs. The second statement tells us why the wasp doesnt lay too many eggs. If it does so, the wasp larvae would die because there would not be enough nutrients and space for all of them.

If too few eggs were laid, portions of the host egg would decay, killing the wasp larvae.

This part tells us what would happen if the wasp laid too few eggs. Laying too few eggs would cause portions of the host egg to decay. This would kill the wasp larvae.


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So, the passage tells us that the parasitic wasp lays neither too few nor too many eggs within the host insects eggs, but exactly the right number.

PRE-THINKING

Which of the following conclusions can properly be drawn from the information above?

The question stem asks us to identify a conclusion that can be drawn from the given information. So, we need to conclude something from the information stated in the passage.

Lets first note down the information given.

1. The parasitic wasp lays its eggs inside the host insects eggs in exactly the right numbers for any suitable size of host eggs.

2. If it lays too many eggs, the larvae die because they compete to the death for nutrients and space.

3. If it lays too few eggs, the larvae die because portions of the host egg decay. Are there any conclusions we can make from any of these statements? We know from statement 2 that the reason wasp larvae would die if too many eggs were laid is that they would not get enough nutrients and space. From this information, we cant conclude anything else about what would happen if too many eggs were laid. Similarly, from statement 3, we know that the reason wasp larvae would die if too few eggs were laid is that portions of the host egg would decay. From this information, we cant conclude anything else about what would happen if too few eggs were laid.

So, the conclusion we need to make will probably come from statement 1. While we cant make an exact prediction about what the conclusion will be, we can narrow down our choices to an option related to the fact that parasitic wasps lay exactly the right number of eggs for any suitable size of host egg.


A. The size of the smallest host egg that a wasp could theoretically parasitize can be determined from the wasp's egg-laying behavior.

This choice fits the scope of the argument. It refers to the wasps egg-laying behavior, which is what the passage is about. It also tells us about the size of the host egg, which is also referred to in the passage. What exactly does this choice say? It says that if we study the wasps egg-laying behavior, we can determine the size of the smallest host egg that a wasp could theoretically parasitize. That is, we can determine the size of the smallest host egg that a wasp can lay its eggs in. We know from the passage that the parasitic wasp lays eggs in exactly the right number for any suitable size of host egg. So, if we study the egg-laying behavior


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of the wasp and find out size of the egg in which a wasp lays only one egg, we can determine the size of the smallest host egg that the wasp could theoretically lay its own eggs in. Therefore, this choice is the correct answer.

B. Host insects lack any effective defenses against the form of predation practiced by parasitic wasps.

The passage gives no information about the host insects possible defenses against parasitism by wasps. So, we cannot conclude anything from the passage about such defenses.

C. Parasitic wasps learn from experience how many eggs to lay into the eggs of different host species.

From the information presented in the passage, we cannot determine how the wasp knows exactly how many eggs to lay. It is possible that the wasps knowledge is hereditary rather than learned from experience.

D. Failure to lay enough eggs would lead to the death of the developing wasp larvae more quickly than would laying too many eggs.

From the passage, we know the two ways in which wasp larvae can die if the wasp does not lay exactly the right number of eggs. But we cannot conclude which way would kill the larvae more quickly. So, this choice cannot be derived from the passage.

E. Parasitic wasps use visual clues to calculate the size of a host egg.

From the passage, we know that the wasp knows exactly how many eggs to lay. However, we cannot conclude that the wasp uses visual clues to calculate the size of a host egg. There could be some other way in which the wasp is able to identify how many eggs to lay for a suitable size of host egg.

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