Problem-Solving and Data Analysis practice question

Answer: 92

The first 6 scores total 6 × 78 = 468. After adding a 7th, the total must be 7 × 80 = 560. The 7th score = 560 − 468 = 92. The trap is assuming the new score equals the new mean (80) or just adding the 2-point rise to 78.

Common wrong answers

If you answered 12

You used 6 × 80 = 480 for the new total, but there are 7 scores after the addition: 7 × 80 = 560, and 560 − 468 = 92.

If you answered 14

You compared 7 × 80 = 560 with 7 × 78 = 546, but only six scores existed at the old mean; the original total is 6 × 78 = 468, so the new score is 560 − 468 = 92.

If you answered 80

That's the new mean, not the new score — a 7th score of exactly 80 would only hold the average where it was if the first six already averaged 80. Compare the totals: 7 × 80 = 560 versus 6 × 78 = 468.

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