Posted by Kathryn on .
If X is a random variable with distribution X~N(350,110)
find (a)P(X<400) and b)P(250<X<400)

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