Reconsider Exercises 3.3.24, 3.3.25, and 3.3.26 about the average number of states all students at the author’s school have visited. Using the data from the author’s sample, a 99% confidence interval for the average number of states all students at the author’s school have visited is found to be (12.97, 17.11). For each of the statements in (a)–(f), say whether VALID or INVALID. 

a. We are 99% confident that the average number of states visited by the 136 students the author surveyed is between 12.97 and 17.11. 

b. Based on the 99% confidence interval, there is evidence that the number of states all students at the author’s school have visited is different from 12. 

c. Based on the 99% confidence interval, there is evidence that the number of states all students at the author’s school have visited is 12. 

d. We are 99% confident that the average number of states visited by all students at the author’s school is between 12.97 and 17.11. 

e. About 99% of the students at the author’s school have visited between 12.97 and 17.11 states. 

f. If we want to be less than 99% confident, we should take a smaller sample of students.

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.