Suppose that the distribution of net typing rate in words per minute (wpm) for experienced typists can be approximated by a normal curve with mean 54 wpm and standard deviation 15 wpm. (Round all answers to four decimal places.)
(a) What is the probability that a randomly selected typist's net rate is at most 54 wpm?
(b) What is the probability that a randomly selected typist's net rate is between 39 and 84 wpm?
(c) Suppose that two typists are independently selected. What is the probability that both their typing rates exceed 84 wpm?
(d) Suppose that special training is to be made available to the slowest 20% of the typists. What typing speeds would qualify individuals for this training? (Round the answer to one decimal place.)