Chapter 6, Problem 6.7P

$\boxed{SOC}$ A random sample of 429 college students was interviewed about a number of matters. Use the results to construct confidence interval estimates of the population mean at the 99% level.

a. They reported that they had spent an average of $\$478.23$ on textbooks during the previous semester, with a sample standard deviation of $\$15.78$.

b. They also reported that they had visited the health clinic an average of 1.5 times a semester, with a sample standard deviation of 0.3.

c. On the average, the sample had missed 2.8 days of classes per semester because of illness, with a sample standard deviation of 1.0.

d. On the average, the sample had missed 3.5 days of classes per semester for reasons other than illness, with a sample standard deviation of 1.5.