Daily output of Marathon'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.

Question

Find the probability of producing..
a.
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

Answer 1

A wonderful little applet here:

http://davidmlane.com/hyperstat/z_table.html

Just enter the mean and sd, and then click on the suitable "between", "below" etc with the given values.

(To my way of thinking, I really see no difference between using the traditional use of tables, graphs, or charts for these kind of problems and this particular little program.)

Answer 2

223