Applied Percent of Decrease and Increase

Day 4

Applied Percent of Decrease

There are situations when the percent of change is going to be a decrease. Examples are:

• Discounts• Sales• Reduction in Population

When finding a discount, there are two different methods you can use.

Method 1:Find the percent of the original price (discounted amount in $)Subtract the discount from the original price.

Method 2:Subtract the percent from 100% (percent you are paying)Find the percent of the original price.

Example: A $50 sweater is on sale for 20% off. Calculate the sale price.Method 1:Find the percent of the original price (discounted amount in $)Subtract the discount from the original price.

Method 2:Subtract the percent from 100% (percent you are paying)Find the percent of the original price.

(Discount)(Sale price)

(Percent you pay)(Sale price)

A manager wants to provide a 30% discount for everything in his store. Find the sale price of a $25 sweater.

Using either method, the answer is $17.50

(Discount)(Sale price)

(Percent you pay)(Sale price)

Click to view Method 1 Click to view Method 2

Click to view answer

The manager has pants, priced at $45, that he needs to mark down 35%. What will be the sale price of the pants?

The pants are on sale for $29.25

(Discount) (Percent you pay)(Sale price)(Sale price)

Click to view Method 1 Click to view Method 2

Click to view answer

Mark wants to purchase a stereo that is on sale, if he is saving at least 30%.

The stereo's original cost is $425.What is the most that he is willing to pay for the stereo?

(Discount)(Sale price)

(Percent you pay)(Sale price)

He is willing to pay $297.50 for the stereo.Click to view Method 1 Click to view Method 2

Click to view answer

50 Decrease 400 by 10%

51 A $710 computer is to be discounted 30%. What will be the sale price?

52 A necklace, priced at $120, is to be marked down 15%. What will be the sale price?

53 The student population of the high school will decrease by 5% next year. The current population is 1407 students. How many students will attend next year?

54 The store is having a 40% off sale. What percent will the customers pay?

55 $80 boots are on sale for 20% off. After the sale, the manager raises the price 20%. What will be the selling price of the boots after the sale?

Applied Percent of Increase

There are situations when the percent of change is going to be an increase. Examples are:

• Tips• Sales Tax• Increase in Population

When finding an increase, there are two different methods you can use.

Method 1:Find the percent of the original price (increased amount)Add the increase to the original price.

Method 2:Add the percent to 100% (percent you are paying)Find the percent of the original price.

Finding a New Amount

Increase 55 by 20%

(Mark up)

(New cost)

(Percent you pay)

(New cost)

Put in notes the above examplesof both methods

Find the new amount

Increase 60 by 10%

Increase 68 by 12%

56 Increase 36 by 25%.

57 Increase 40 by 15%

Tip: An amount added to a bill for services provided. Customers traditionally tip 18 - 20% for good service in restaurants and salons.

Example:If the restaurant bill is $45 and you want to leave a 20% tip, how much money should you leave?

45 + .20(45) = 54  or  45(1.20) = 54

The customer will leave $54 on the table. The waitress will receive a $9 tip and the restaurant will receive $45.

To calculate the amount of the tip only:

.20(45) = 9

Calculate a 20% tip on a $75 bill.

What will the customer leave in total?

For poor service, my friend will leave a 5% tip.How much less will this waitress earn than the waitress above?

Sales tax: An amount of money that is calculated by applying a percentage rate to the taxable price of a sale. Sales taxes are collected by the buyer from the seller, who turns it over to the government. In NJ the sales tax rate is 7%.

To calculate Sales Tax alone find the percent (tax) of the price. That is the amount that you owe in addition to the cost of the item.

To find the total cost of an item, you must add the sales tax to the cost. There are 2 ways to do this:

1. Find the percent of the item and add it to the original amount.

2. Find 100% + tax% of the original amount.

A car costs $23,500. How much sales tax will the customer pay?

23,500(0.07) = $1645

What will the customer pay altogether for the car?

23,500 + 1645 = $25,145

The total cost of the car, including tax, can be calculated as follows:

23,500 + .07(23,500) = 25,145 or 23,500(1.20) = 25,145

Discuss: How are tips and sales tax alike?

58 What is the total cost of a $250 stereo with a 7% sales tax?

59 Calculate the sales tax on a $125 bicycle.

60 Mike wants to leave a 20% tip. His bill is $35.50. How much is the tip?

61 A $65 restaurant tab (bill) is put on the table. The couple plans on leaving an 18% tip. How much should be left altogether?

62 What is the total cost of a $123 ipod, including tax of 5.5%?