Posted by diana on .
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

statistics 
PsyDAG,
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.