49. In a survey, students gave their study time per week

(hr), and here are the 22 values:

15.0 10.0 10.0 15.0 25.0 7.0 3.0 8.0 10.0 10.0 11.0 7.0 5.0 15.0 7.5 7.5 12.0 7.0 10.5 6.0 10.0 7.5 We would like to get a 95% con dence interval for the population mean.

a. Compute the t-based con dence interval of Section 8.3.

b. Display a normal plot. Is it apparent that the data set is not normal, so the t-based interval is of questionable validity?

c. Generate a bootstrap sample of 1000 means.

d. Use the standard deviation for part

(c) to get a 95% con dence interval for the population mean.

e. Investigate the distribution of the bootstrap means to see if part

(d) is valid.

f. Use part

(c) to form the 95% con dence interval using the percentile method.

g. Say which interval should be used and explain why.