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In a certain first grade classroom, the average height is

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by M7MBA » Tue Apr 30, 2019 12:49 am

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In a certain first grade classroom, the average height is \(x\) inches for the 5 girls and \(y\) inches for the 8 boys. What is the average height for the 13 students in the classroom combined?

(1) \(15x + 24y = 1755\)
(2) \(x < 40\)

[spoiler]OA=A[/spoiler]

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by Ian Stewart » Tue Apr 30, 2019 3:30 am
The sum of the 5 girls' heights is 5x, and the sum of the 8 boys' heights is 8y, so the average height is (5x + 8y)/13. So if we can find the value of 5x + 8y, we can answer the question.

From Statement 1, dividing by 3 on both sides, we find

15x + 24y = 1755
5x + 8y = 1755/3

so we can find the value of 5x + 8y, and therefore answer the question. Statement 2 isn't helpful, so the answer is A.
For online GMAT math tutoring, or to buy my higher-level Quant books and problem sets, contact me at ianstewartgmat at gmail.com

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