According to e-Marketer, adults in the United States average 82 minutes per day on mobile devices in 2012. Assume that minutes per day on mobile devices follow the normal distribution and has a standard deviation of 27 minutes.
a. What is the probability that the amount of time spent today on mobile devices by a particular U. S. adult is
1. less than 70 minutes?
2. more than 65 minutes?
3. between 85 and 110 minutes?
b. Confirm the answers to part a using Excel or PHStat.
c. Which number of minutes per day represents the 75th percentile?