Question

The ages of students in a school are normally distributed with a mean of 15 years and a standard deviation of 2 years. Approximately what percent of the students are between 14 and 18 years old?

a. 24.17%
b. 62.47%
c. 30.85%
d. 93.32%

Answer 1

62.47

Explanation:

Answer 2

P(14 < X < 18) = P(X < 18) - P(X < 14) = P(z < (18 - 15)/2) - P(z < (14 - 15)/2) = P(z < 3/2) - P(z < -1/2) = P(z < 1.5) - [1 - P(z < 0.5)] = P(z < 1.5) + P(z < 0.5) - 1 = 0.93319 + 0.69146 - 1 = 1.62465 - 1 = 0.62465

Therefore, approximately 62.47% ofthe students are between 14 and 18 years old.