Statistics
posted by Bill on .
Assume the weights of men are normally distributed having a mean of 185 lbs and a standard deviation of 17 pounds.
A. Calculate the probability a randomly selected man weights less than 225 lbs
B. Approximately 72% of men’s weights exceed how many pounds.
C. In a random example of 50 men, calculate the probability their mean weights is no more than 180 pounds.
D. In a random example of 50 men, approximately 8% of all possible men’s weights will exceed how many pounds.

A, B. Z = (scoremean)/SD
Find table in the back of your statistics text labeled something like "areas under normal distribution" to find the proportion/probability (B use.72) related to the Z score.
Last two problems relate to distribution of means rather than a distribution of raw scores.
C, D. Z = (scoremean)/SEm
SEm = SD/√n
Use same table.