The average waiting time to be seated for dinner at a popular restaurant is 23.5 minutes, with a standard deviation of 3.6 minutes. Assume the variable is normally distributed. When a patron arrives at the restaurant for dinner, find the probability that the patron will have to wait the following time.
a. Between 15 and 22 minutes
b. Less than 18 minutes or more than 25 minutes
c. Is it likely that a person will be seated in less than 15 minutes?