Question

Markus scored 85, 92, 82, and 94 on the first four tests of the semester. His teacher has not yet told him his score on his fifth test, but did tell him that his score on the fifth test is five points lower than the average (arithmetic mean) of all five tests. Which equation could Markus use to determine the score of the fifth test, x?

Answer 1

Call x the score on his fifth test. Then the average (arithmetic mean) of the five test will be: (85 + 92 + 82 + 94 + x) / 5. That is equal to (353 + x ) / 5. The teacher said that the new score, x, is 5 points lower than the average, then x = (353 + x) / 5 - 5 . Answer: Markus could use the equation x = (353 - x)/ 5 - 5 (or an equivalent form of it)

Answer 2

The answer is B. 5(x + 5) = 353 + x

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