In a population of scores X 83 corresponds to z 050 and X

In a population of scores, X = 83 corresponds to z = –0.50 and X = 93 corresponds to z = +2.00. What are the values for the population mean and standard deviation?

a.

= 85 and = 4

b.

= 85 and = 2

c.

= 81 and = 4

d.

= 81 and = 6

Solution

As

x = u + z s

Then

83 = u - 0.50 s
93 = u + 2.00 s

Solving for u and s in this system,

u = 85
s = 4 [ANSWER, OPTION A]