2. A publisher wants to estimate the mean length of time (in minutes) all adults spend reading newspapers. To determine this estimate, the publisher takes a random sample of 15 people and obtains the following results:

11, 9, 8, 10, 10, 9, 7, 11, 11, 7, 6, 9, 10, 8, 10

Assume that the population of times is normally distributed.

a. Find the point estimate of the population mean.

b. Construct the 95% confidence interval for the mean population length reading time and interpret it.

c. What is the margin of error?

d. How can we reduce the margin of error?