At a medical clinic, patient office visits are found to last a mean time of 17 minutes, with a standard deviation of 10 minutes. Assume that the probability distribution of time is independent from one patient to another.
a. What is the approximate probability that the 25 patients scheduled for tomorrow will require more than 7 hours altogether?
b. What is the approximate probability that the average time for 25 patients will be more than 20 minutes?