Time spent using email per session is normally distributed, = 10 minutes and = 2 minutes. If you select a random sample of 4 sessions,

a.What is the probability that the sample mean is less than 8 minutes?

b.What is the probability that sample mean is between 8 and 9minutes?

c.If you select a random sample of 16 sessions, what is the probability that a as sample mean is between 8 and 9 minutes?

d.Explain the differences in the results of (b) and (c).