Area Below Positive Z
(A worked Problem:  Procedure explained in more detail in Chapter 7)

Suppose that a personality test has:

Mean = 200
Standard Deviation = 50

What is the proportion of people taking this test that score below 210?

I.  First you must convert the original score to a Z score.

II.  Because the Z score is positive and we want to find the area below then:

    A.  We can find the pink shaded area in Column 2 of Table Z = .0793

    B.  Remember that there is .5 on either side of the mean

III.  Therefore the area below = Column 2 + .5 = .0793 + .5 = .5793 or 57.93%

Copyright © 2004 by Mark W. Vernoy