In order to get accepted into graduate school, you know you must score in the top 20% of scores on a standardized test.

Question

If the test has a mean score of 800 and a standard deviation of 125, what is the lowest score you can achieve and still be admitted to the graduate school?

Answer 1

Assumption: normally distributed

 

If 20% must score above, 80% must score below.

The z value below which 80% of area falls can be obtained form the Excel function "=normsinv(.80)", or from a table.

z= .8416

 

score = mean + z*sd = 800 + .8416*125 = 905.2

 

Minimum score is 906