2010 AMC 10B Problem 15

Below is the professionally curated solution for Problem 15 of the 2010 AMC 10B, from LIVE by Po-Shen Loh. You can also try the full timed exam, view all 2010 AMC 10B solutions, or check the answer key.

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Concepts:linear equationinequalityoptimization

Difficulty rating: 1420

15.

On a 5050-question multiple choice math contest, students receive 44 points for a correct answer, 00 points for an answer left blank, and 1-1 point for an incorrect answer. Jesse’s total score on the contest was 99.99. What is the maximum number of questions that Jesse could have answered correctly?

2525

2727

2929

3131

3333

Solution:

Let xx be the number of questions Jesse answered correctly and yy be the number he answered incorrectly.

Then 4xy=99 and x+y50. 4x - y = 99 \text{ and } x + y \leq 50.

We have that y=4x99 y = 4x - 99 5x9950. 5x - 99 \leq 50.

Rearranging and simplifying tells us that x29.8.x \leq 29.8. Since xx is an integer, its maximum value is 29.29.

Thus, C is the correct answer.

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