Suppose that the waiting time for a pizza to be delivered to an individual's residence has been found to be normally distributed with a mean of 30 minutes and a standard deviation of 8 minutes. What is the probability that a randomly selected individual will have a waiting time:
a) between 15 and 45 minutes?
b) At least 10 minutes?
c) At most 10 minutes?
d) No more than 45 minutes?