PSAT Math Multiple-Choice Question 282: Answer and Explanation

Question: 282

Professor Murphy received an end of the year evaluation from her 6 superior faulty members. Her overall rating for her yearly work was a 9.5. If five faculty members told her that they rated her work at 8.7, 9.6, 9.9, 9.9 and 9.4, what was the rating from the last faculty member?

• A. 8.9
• B. 9.1
• C. 9.5
• D. 9.9

Correct Answer: C

Explanation:

Professor Murphy’s evaluation is an average of all six of the faculty scores. The added values of her ratings should be equal to 57 because her overall score of 9.5 × 6 scores = 57. The sum of all of her known scores equal 47.5 and the difference of the total to her known sum equals the final score. 57 - 47.5 = 9.5. See Lesson: Equations with One Variable.