Statistics Question on Standard Units?

Question

Here is the problem...I don't know where to start it:::

A personality test is administered to a large group of subjects. Five scores are shown below, in orgincal units and in standard units. Fill in the blanks (question marks).

79----1.8
64----0.8
52----(?)
72----(?)
(?)---- -1.4 <---negative 1.4

I know how to get sd and standard units in normal problems...but I have no idea where to start for this one...thanks for any help.

Answer 1

good problem!
the standard deviation is 15. you can figure this out by the values between 79 (1.8) and 64 (.8)
from there you can extrapolate to find the mean.
15 x 1.8 =27
79-27 = 52 52= 0
72-52/15 = 20 = 1.333
-1.4 31-52/15 = -1.4
52= 0
72= 1.33
31= -1.4
hope this helps

Answer 2

The first two values give you the givens needed to solve the problem

Z=(x-u)/s^2 for simplicity let's call s^2, d

1.8=(79-u)/d ===>1.8d=79-u

0.8=(64-u)/d ===> .8d=64-u

This gives you 2 equations and 2 unknowns.

d=15, u=52

The rest you can plug in and get the results.