Chapter 7, Problem 78SE

Preschool: Just the Boys Refer to Exercise 7.77 for information. This data set records results just for the boys.

a. Find and compare the percentages that graduated for each group, descriptively. Does this suggest that preschool was linked with a higher graduation rate?

b. Verify that the conditions for a two-proportion confidence interval are satisfied.

c. Indicate which one of the following statements is correct.

i. The interval does not capture 0, suggesting that it is plausible that the proportions are the same.

ii. The interval does not capture 0, suggesting that it is not plausible that the proportions are the same.

iii. The interval captures 0, suggesting that it is plausible that the population proportions are the same.

iv. The interval captures 0, suggesting that it is not plausible that the population proportions are the same.

d. Would a $99\%$ confidence interval be wider or narrower?