Posted by Mary Ann on Sunday, January 8, 2012 at 9:30pm.
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?

Statistics  PsyDAG, Monday, January 9, 2012 at 11:44am
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. 
Statistics  Cris, Saturday, April 6, 2013 at 10:38pm
What do you mean "Z" scores in relation to the problem above? sorry, I'm totally confused and overwhelmed