2025 AMC 8 Problem 14

Attempt Problem 14 of the 2025 AMC 8 below, then check your answer against the video solution and professionally curated solution from LIVE by Po-Shen Loh. You can also try the full timed exam, view all 2025 AMC 8 solutions, or check the answer key.

All problems are used with official legal permission of the Mathematical Association of America (MAA).

14.

A number NN is inserted into the list 2,2, 6,6, 7,7, 7,7, 28.28. The mean is now twice as great as the median. What is N?N?
77
1414
2020
2828
3434
Answer: E
Concepts:meanmedian (data)
Small hint:
Since every choice is at least 7,7, the median stays fixed
Big hint:
Make the total sum equal to 66 times twice the median
Video solution:
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Written solution:
After inserting NN into the list, there will be 66 total numbers. That is even, so the median will be the average of the middle two numbers.
All of the answer choices are at least 7,7, so when they are inserted into the list, the middle two numbers will be 77 and 7.7. It is convenient that the median will always be 7,7, no matter which answer choice is picked.
The mean becomes twice the median, which is 2×7=14.2 \times 7 = 14.
To have a total of 66 numbers with mean 14,14, their sum must become 6×14=84.6 \times 14 = 84.
The sum of the original 55 numbers is 2+6+7+7+28=50, 2 + 6 + 7 + 7 + 28 = 50, so the answer is 84−50=34,84 - 50 = 34, which is choice E.
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