MathDB
Test scores

Source:

February 20, 2006

Problem Statement

Mrs. Walter gave an exam in a mathematics class of five students. She entered the scores in random order into a spreadsheet, which recalculated the class average after each score was entered. Mrs. Walter noticed that after each score was entered, the average was always an integer. The scores (listed in ascending order) were 7171, 7676, 8080, 8282, and 9191. What was the last score Mrs. Walter entered? (A) 71(B) 76(C) 80(D) 82(E) 91\text{(A)}\ 71 \qquad\text{(B)}\ 76 \qquad\text{(C)}\ 80 \qquad\text{(D)}\ 82 \qquad\text{(E)}\ 91