1. An instructor wanted to construct a confidence interval for the mean GPA of the students in his class. He used the campus records system to obtain their GPA's and computed the 95% interval as (2.32, 2.87). If he wants to use this interval to describe the students in his class,
A. he's 95% confident the interval contains the real average GPA.
B. there's a 5% chance the interval is wrong.
C. he didn't need an interval after all.
2. A student curious about the average number of chocolate chips in a commercial brand of cookie estimated the standard deviation to be 8. If he wants to be 99% confident in his results, how many chocolate chip cookies will he need to sample to estimate the mean to within 2?
A. 11
B. 107
C. 62
3. A student wanted to estimate the number of chocolate chips in a commercial brand of cookie. He sampled 100 cookies and found an average of 10.5 chips per cookie. If we assume the standard deviation is 8, what is a 99% confidence interval for the average number of chips per cookie?
A. (8.4, 12.6)
B. (8.9, 12.1)
C. (5.3, 10.7)