Time spent using e-mail per session is normally distributed, with µ=8 minutes and standard deviation = 2 minutes. If you select a random sample of 25 sessions,
A. what is the probability that the sample mean is between 7.8 and 8.2 minutes?
B. what is the probablility that the sample mean is between 7.5 and 8 minutes?
C. if you select a random sample of 100 sessions, what is the probablility that the sample mean is between 7.8 and 8.2 minutes?
D. explain the difference in the results of (a) and (c).