Statistics
posted by Mary Ann .
Daily output of Marathonâ€™s Garyville, Lousiana, refinery is normally distributed with a mean of
232,000 barrels of crude oil per day with a standard deviation of 7,000 barrels. (a) What is the
probability of producing at least 232,000 barrels? (b) Between 232,000 and 239,000 barrels?
(c) Less than 239,000 barrels? (d) Less than 245,000 barrels? (e) More than 225,000 barrels?

Z = (scoremean)/SD
Find table in the back of your statistics text labeled something like "areas under normal distribution" to find the proportions that correspond to the Z scores. 
What do you mean "Z" scores in relation to the problem above? sorry, I'm totally confused and overwhelmed