AP Biology Chi-Squared PracticeProblems

(Set 2)

The integration of analytical skills in the AP Biology course has anew challenge for AP Biology teachers. In an attempt to facilitate studentmastery of unfamiliar skills I have chosen to front-load analytical skills intobeginning of my course. My students will be assessed with a minimum of 5 grid-in

on each unit exam.I have experienced extreme difficulties finding chi-squared problems that

are not all content specific, but still appropriate for the course. In order toimplement the course long strategy I needed a bank of problems that studentscould complete at any time in the course. I've decided to pass these problems I'vedeveloped on to the AP Biology teachers who are experiencing the same struggle!

Chi-Squared Formula: x 2 =

Critical Values:

(O-E)2 Where:O Observed ResultE Expected Result

• Sum of

Degreesof

Freedom 0

2 no3 J85

.1129

5 .752

level] of Proba[öülåfiy (P)

.004

.03

.352

n.1115

080.064

.466

L005

L611q

2.343

so.1155

2.366

3.357

020

4.64

5.qq

7.2q

.10

2.71

4.61

6.25

7.78

q.211

.053.84

5.qq

7.82

ILO?

.025.41

7.82

167

13.39

.01

6.64

9.21

135

13.28

s."

.00]0.83

13.82

18.47

20.52

I. When studying animal behavior, the distribution of organismswithin a choice chamber can be studied to identify animalpreferences. 100 Isopods are placed in a Il-choice choicechamber. A cotton ball dampened with distilled water is placedin Chamber A; A cotton ball dampened with vinegar is placed inchamber B, a cotton ball dampened with cough medicine isplaced in chamber C, and a cotton ball dampened with soda isplaced in chamber 10. After 15 minutes 17 isopods are in chambera; 8 isopods are in the chamber with vinegar, 35 isopods are in thechamber with the cough medicine, and 40 isopods are in thechamber with the soda . Perform the chi-squared test todetermine if the distribution of isopods is significant or due torandom chance. (3 points)

a. Complete the grid inspace with the chi-squared value.

o oree. 0-0.

O ORO0000000000000000000000000eooee0000000000

b. Complete the grid inspace with the criticalvalue.

0000000000000000000oÄooo00000obo""

c. Do you reject the null hypothesis?Yes or No

2. When studying animal behavior, the distribution of organismswithin a choice chamber can be studied to identify animalpreferences. 8 isopods are placed into a two choice chamber.Chamber A is covered in red paper; chamber B is covered in bluepaper. After 15 minutes 6 isopods are in chamber A, 2 isopods arein chamber B. Perform the chi-squared test to determine if thedistribution of isopods is significant or due to random chance. (3points)

a. Complete the grid inspace with the chi-squared value.

ROOO000000000000000900000000000000o o ONOboooo0606b

b. Complete the grid inspace with the criticalvalue.

popgoo R

000000000000000boooo0000900000opopgodooob Bbob

c. Do you reject the null hypothesis?Yes or No

3. A scientists proposes that mosquitoes prefer individuals with acertain blood type. 33 mosquitoes are allowed to choose to drinkfrom samples of blood with 3 types: A, B, and O. After 2 hours the15 mosquitoes drank A type blood, Il mosquitoes drank B typeblood, and 7 mosquitoes drank O type blood. Use a chi squareanalysis to determine if mosquitoes prefer to drink one bloodt e over another (3 oints).

a. Complete the grid in b. Complete the grid inspace with the chi- space with the criticalsquared value.

e eggggodoro

oddbbß

bbdobq0000bhod d hob*b o db bhoqoobbbq d>b«b b dob

value.

moopme oUUdo'0000

o W ho*op«ood

do 04900660

p o bdbd

oto

c. Do you reject the null hypothesis?Yes or No

q. Chase insists that Mondays are the worst, and students are morelikely to be tardy on Mondays. In an effort to convince theprincipal to grant a 10 minute tardy grace period on WednesdaysChase collects tard data on 50 students for one week.Week Da Monda Tuesda Wednesda Thursda Frida# tard 12 13 6 12 7Use a chi square analysis to see if Chase is correct, and if studentsare si nificantl more likel to be tard on Monda s.

a. Complete the grid in b. Complete the grid inspace with the chi-squared value.

eeeeee0 000

000000000000000000000000000000eeooo0000000000

space with the criticalvalue.

00000000000000

odooo0900000000oeoeo00000

c. Do you reject the null hypothesis?Yes or No

5. An angry group of parents have petitioned for the right to choosethe music played at prom. The parents suggest that the type ofmusic played increases the likelihood of inappropriate PDAbetween teens. An enterprising AP biology class decides todisprove the parents by measuring the instances of publicdisplays of affection that occur during different songs at a smalldance. The group studies 24 students. Perform a chi-squaredanalysis to determine if the music playing effects the numbers ofPDA s ina ro of teens.

Hip HOP Country Metal Classics# PDAS 8 7 3 6

a. Complete the grid in b. Complete the grid inspace with the chi-squared value.

0000000000000000000bÅoYo0000000000

space with the criticalvalue.

0000060000000000000boooöo RdNN0000000000

c. Do you reject the null hypothesis?Yes or No