According to social media blog, time spent on Tumblr, a microblogging platform and social networking website, has a mean of 28 minutes per visit and the standard deviation of the time spent on Tumblr per visit is 5 minutes.
a) How would you determine your sample size “n”?
b) If you select a random sample of 40, what is the probability that your sample will have a mean above 30 minutes?
c) If you select a random sample of 50, what will be the lower limit and upper limit of the interval symmetrically distributed around the population mean that includes 80% of the sample means?
Sample Solution