Question

The following graph shows the normal distribution of the results of an algebra test a class of 22 students took.

The median of the results was 80 points out of 100, with a standard deviation of 6 points.
Which of the following numbers is closest to the number of students that got more than 86 but less than 92 points?
1
3
7
9

Answer 1

The score of 86 is equal to a z-score of (86 - 80)/6 = 1. The score of 92 is equivalent to (92 - 80)/6 = 2. This falls within the +1sigma to +2sigma, which has 13.59% under that range. Since there are 22 students in total:
(0.1359)(22) ~ 3 students