A testing bureau reports that the mean for the population of Graduate Record Exam (GRE) scores is 500 with a standard deviation of 90. The scores are normally distributed. The proportion of scores that lie above 650 is _________.
A) 0.4535
B) 0.9535
C) 0.0475
D) 0.0485

Question

Quizplus · Accepted Answer

First, we need to standardize the score of 650. 
$z=\frac{650-500}{90}=1.67$
Then we need to find the proportion of scores that lie above 650, which corresponds to the area to the right of 1.67 on the standard normal distribution table. Using a table or calculator, we can find this area to be 0.0475, which is the answer choice C.

A Testing Bureau Reports That the Mean for the Population