Question

Suppose you have a normally distributed set of data pertaining to a standardized test. The mean score is 1000 and the standard deviation is 200. What is the z-score of 900 point score?

Answer 1

The z-score is given by the formula:
z=(x-mean)/s.d
given that:
x=900
mean=1000
s.d=200
therefore the z-score will be:
(900-1000)/200
=-0.5

the answer is -0.5