Test scores on a statewide standardized test for a large population of students are normally distributed with mean = 9.44 and standard deviation = 1.75. certificates are given to students who score in the top 2.5% of those who took the test. fred, a student who took the test, finds out that he earned a score of 13.1 on the test. he will not get a certificate

Since about 95% of a normal distribution falls within two standard deviations of the mean , it follows that 5% lie outside this range, with 2.5% lying to either side of it.This means , with the remaining 2.5% lying above .

This means for a score to belong in the top 2.5%, it's corresponding z-score must be higher than 2.

Fred scores 13.1 on the test. The corresponding z-score is



which is barely higher than 2, but high enough to earn that certificate.