Posted by Aditi on Friday, June 24, 2011 at 1:58am.
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?

statistics  PsyDAG, Friday, June 24, 2011 at 11:49am
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.