2023 AMC 8 Problem 25
Below is the video solution and professionally curated solution for Problem 25 of the 2023 AMC 8, from LIVE by Po-Shen Loh. You can also try the full timed exam, view all 2023 AMC 8 solutions, or check the answer key.
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Difficulty rating: 1950
25.
Fifteen integers are arranged in order on a number line. The integers are equally spaced and have the property that and
What is the sum of the digits of
Video solution:
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Written solution:
Let be the common difference. If we let and we see that Since all the numbers are integers, must be at least
Also, if and we get that Once again since all the numbers are integers, is at most This tells us that is
Note that This means that must be at least for to be within the desired range.
If is greater than however, becomes greater than which is not allowed.
Now we know that and This tell us that
Therefore, sum of the digits is
Thus, A is the correct answer.
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