According to a mashable.com post, time spent on Tumblr, a micro blogging platform and social networking website, has a mean of 14 minutes per visit. (Source: on.mash.to/1757wfE.) Assume that time spent on Tumblr per visit is normally distributed and that the standard deviation is 4 minutes. If you select a random sample of 25 visits,
a. what is the probability that the sample mean is between 13.6 and 14.4 minutes?
b. what is the probability that the sample mean is between 13 and 14 minutes?
c. If you select a random sample of 100 visits, what is the probability that the sample mean is between 13.6 and 14.4 minutes?
d. Explain the difference in the results of (a) and (c).