statistics
posted by Aditi .
mean = 60 wpm
standard deviation= 15 wpm
a.What is the probability that a randomly selected typist's net rate is at most 60 wpm? less than 60 wpm?
b. What is the probability that a randomly selected is between 45 and 90 wpm?

Z = (scoremean)/SD
Find table in the back of your statistics text labeled something like "areas under normal distribution" to find the proportions/probabilities related to the Z scores.