# Chi Square Practice Problems

Solve all problems using a chi square analysis. You must use statistics to support your answers.

1. A zookeeper hypothesizes that changing the intensity of the light in the primate exhibits will reduce the amount of aggression between the baboons. In exhibit A, with a lower light intensity, he observes 36 incidences of aggression over a one month period. In exhibit B, with normal lights, he observes 42 incidences of aggression. Should he support or reject his hypothesis?

2. A high school, students can choose to enter one of three doors. Custodians noticed that door #3 was always getting broken and suggested that more students use that door because it has a hands-free opener. Science minded students counted the number of students entering each door to see if the custodians were right.

Door #1 had 60 students enter | Door #2 had 56 students enter | Door #3 had 94 students enter.

Were the custodians right?

3. A scientist predicts that the kittens born with a congenital birth defect will be 25% based on the hypothesis that it is caused be a recessive gene in that breed of cat. After surveying several litters, he found that 44 out of 128 kittens had the defect. Is his hypothesis correct?

4. Suppose you take a random sample of 30 students who are using a new math text and a second sample of 30 students who are using a more traditional text. You compare student achievement on the state test given to all students at the end of the course. Based on state test performance, would you recommend the new math book?

 Passed State Test Failed State Test New Textbook 26 4 Old Textbook 22 8

## Other Resources on Chi Square

Slides on Chi Square Analysis

Chi Square with Candy

Scary Pumpkin Statistics