For a sample of n 30 scores a score that is 6 points above

For a sample of n = 30 scores, a score that is 6 points above the mean has a z-score of z = 1.50. What is the sample standard deviation?

a.

4

b.

6

c.

8

d.

12

Solution

As for samples,

z = (x - u) / s

(the sample size is not included, because we are just talking about scores.)

As (x - u) = 6, z = 1.50,

1.50 = 6 / s

Thus,

s = 4 [ANSWER, OPTION A]