Suppose that the waiting time for a license plate renewal at a local office of a state motor vehicle department has been found to be normally distributed with a mean of 30 minutes and a standard...

Suppose that the waiting time for a license plate renewal at a local office of a state
motor vehicle department has been found to be normally distributed with a mean of
30 minutes and a standard deviation of 8 minutes.
i. What is the probability that a randomly selected individual will have a waiting
time of at least 10 minutes?
ii. What is the probability that a randomly selected individual will have a waiting
time between 15 and 45 minutes?
iii. Suppose that in an effort to provide better service to the public, the director of
the local office is permitted to provide discounts to those individuals whose
waiting time exceeds a predetermined time. The director decides that 15
percent of the customers should receive this discount. What number of
minutes do they need to wait to receive the discount?