statistics
posted by diana .
Assume the monthly rainfall in a certain state is normally distributed with a mean of 2.85 inches and a standard deviation of .2 inches:
a) probability that in any given month there is between 2.7 and 2.9 inches of rainfall
b) probability that in any given month there is more than 2.9 inches of rainfall

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