2015 AMC 10A Problem 5

Below is the professionally curated solution for Problem 5 of the 2015 AMC 10A, from LIVE by Po-Shen Loh. You can also try the full timed exam, view all 2015 AMC 10A solutions, or check the answer key.

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Concepts:mean

Difficulty rating: 870

Mr. Patrick teaches math to $15$ students. He was grading tests and found that when he graded everyone's test except Payton's, the average grade for the class was $80.$ After he graded Payton's test, the test average became $81.$ What was Payton's score on the test?

$81$

$85$

$91$

$94$

$95$

Solution:

The total for the first $14$ graded tests was $14\cdot 80=1120$ .

After Payton's test was included, the total became $15\cdot 81=1215$ . Therefore Payton's score was $1215-1120=95$ .

Thus, E is the correct answer.

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