Question

Mr. Jones’ Algebra 2 classes averaged a 78 on a recent test. He calculated a standard deviation of 4. What percentage of the class received?

A test grade greater than 80:

A test grade less than 50:

A test grade between 66 and 90:

Answer 1

Let ,

a)

; From standard normal distribution table

Therefore , the percentage of the class received a test grade greater than 80 is 30.85%

b)

; From standard normal distribution table

Therefore , the percentage of the class received a test grade less than 50 is 0%

c)

; From standard normal distribution table

Therefore , the percentage of the class received a test grade between 66 and 90 is 99.74%