Question: Time spent using e-mail per session is normally distributed with a population mean of 8 minutes and a standard deviation of 2 minutes. If you select a random sample of 25 sessions: (hint: section 7.2 sampling distribution of the mean)

a. What is the probability that the sample mean is between 7.8 and 8.2 minutes?

b. What is the probability that the sample mean is between 7.5 and 8 minutes?

c. If you select a random sample of 100 sessions, what is the probability that the sample mean is between 7.8 and 8.2 minutes.

d. Comment on the impact that the increase of the random sample from 25 sessions in (a) to 100 sessions in (c) had on the results.