PSAT Math Multiple-Choice Question 639: Answer and Explanation

Question: 639

Given that the average of Mrs. Smith's and Mr. Walker's classes together represents the average enrollment in each English class at the school and that there are a total of 14 English classes, how many total students are enrolled in English classes at the school, assuming that students are enrolled in exactly one English class?

• A. 280
• B. 420
• C. 560
• D. 840

Correct Answer: B

Explanation:

(B) Every student in each class either did or did not complete summer reading. So the total number of students enrolled in Mrs. Smith's class is 29, and the total number enrolled in Mr. Walker's class is 31. The average number of students enrolled in the two classes is:

We can assume that each of the 14 English classes has, on average, 30 people. Therefore, the total number enrolled in English classes would be:

14(30) = 420

The correct answer is choice (B).