Question

In a class of 25 students, the grades were normally distributed with a mean of 78 and a standard

deviation of 6.5. How many students scored above an 87?

Answer 1

Explanation:

The mean is 78

87 is 9 points above the mean

this is 9 / 6.5 = + 1.39 standard deviations above the mean

z -score =+ 1.39 which represents .9177 ( from table )

or 91.77% scored LESS than this

the remaining 8.23% scored HIGHER than this

8.23% * 25 students = .0823 * 25 = ~ 2 students