The Yap family has a total of three members. They spend 30 hours every day on the Internet.

a. Calculate the average time spent on the Internet in a day by each member of the Yap family.

b. If the amount of time spent on the Internet daily is normally distributed, determine the standard deviation of time spent on the Internet by the Yap family. (Hint: Recall the Empirical Rule.)

c. Choose a reasonable confidence level and calculate a confidence interval for the average time spent on the Internet per day by members of the Yap family.