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SUM?

by grandh01 » Mon Aug 20, 2012 2:16 pm
A certain fraction is equivalent to
2/5. If the numerator of the fraction is
increased by 4 and the denominator is
doubled, the new fraction is
equivalent to
1/3. What is the sum of
the numerator and denominator of the
original fraction?
(A) 49 (B) 35 (C) 28
(D) 26 (E) 21

OA is E
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by truplayer256 » Mon Aug 20, 2012 4:10 pm
Let x/y = 2/5.

(x + 4)/(2y) = 1/3 => 1/2(x/y) + 2/y = 1/3

1/5 + 2/y = 1/3 => 2/y = 2/15

y = 15

x = (2/5)(15) = 6

x + y = 21

Choose E.
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by Anurag@Gurome » Mon Aug 20, 2012 7:33 pm
grandh01 wrote:A certain fraction is equivalent to
2/5. If the numerator of the fraction is
increased by 4 and the denominator is
doubled, the new fraction is
equivalent to
1/3. What is the sum of
the numerator and denominator of the
original fraction?
(A) 49 (B) 35 (C) 28
(D) 26 (E) 21

OA is E
Let us assume that the fraction is 2x/5x.
Then (2x + 4)/(10x) = 1/3
6x + 12 = 10x
4x = 12
x = 3
Original fraction = (2 * 3)/(5 * 3) = 6/15
Sum of numerator and denominator = 6 + 15 = 21

The correct answer is E.
Anurag Mairal, Ph.D., MBA
GMAT Expert, Admissions and Career Guidance
Gurome, Inc.
1-800-566-4043 (USA)

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