Problem-Solving and Data AnalysisHardMean after adding a value
Problem-Solving and Data Analysis practice question
The mean of five test scores is 80. A sixth test is taken, and the mean of all six scores becomes 82. What was the score on the sixth test?
Answer: 92
Five scores total 400. Six scores total 6 × 82 = 492. The sixth is 492 − 400 = 92.
Common wrong answers
- If you answered 12
- 12 is 492 − 480, mixing the old and new means.
- If you answered 82
- 82 is the new mean, not the sixth score; the sixth had to be above 82 to raise the mean.
- If you answered 84
- 84 comes from adding the 2-point rise to 82; the rise is spread over six scores, so the sixth is 80 + 6 × 2 = 92.
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