A test is given and the average
(μX) score was 190, with a SD (σX) of 50.
Assuming a normal distribution for the grades, find the dividing
line (test scores) between the A's, B's, C's, D's, and E's. The
bottom 13% will be assigned the E's, the next 13% will be the D's,
50% will be the C's, the next 15% the B's and the top 9% will be
the A's.