math
posted by shirley .
The weights of boxes of Brand Z cereal were found to be normally distrubted with a mean of 16.5 ounces and a standard deviation of 0.4 ounces.
a. what percentage of the boxes will weigh more than 16 ounces?
b. what percentage of the boxes will weigh between 15.5 and 16.5 ounces?
c. if a store has 500 boxes of cereal, how many of them will weigh less than 15.5 ounces?

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.