Reconsider Exercise 3.3.24 about the average number of states all students at the author’s school have visited. Recall that in the author’s sample of 136 students the average number of tates the students had visited was 15.04 and the standard deviation was 9.26. 

a. Use the Theory-Based Inference applet to find a 95% confidence interval for the average number of states all students at the author’s school have visited. 

b. Does the 95% confidence interval that you have reported in part (a) provide evidence that the average number of states all students at the author’s school have visited is different from 12? 

c. In the context of this study, was it valid to use the theory-based (t-distribution) approach to find a confidence interval? Explain your reasoning.

Data from Exercise 3.3.24

IPSOS opinion and public research company surveyed 2,010 adult Americans and found that, on average, Americans have visited 12 states in the United States. In a survey of 136 statistics students at the school where one of the authors teaches, the average number of states visited was 15.04 and the standard deviation was 9.26. The data were not strongly skewed.