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Linear Equation

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Linear Equation

by crackgmat007 » Tue May 05, 2009 9:37 am
E. If x, y, and k are positive numbers such that (x/ y+x) * (10) + (y/x+y) * (20) = k and if x < y, which of the following could be the value of k?
A. 10
B. 12
C. 15
D. 18
E. 30

OA - D
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Re: Linear Equation

by dtweah » Tue May 05, 2009 10:05 am
crackgmat007 wrote:E. If x, y, and k are positive numbers such that (x/ y+x) * (10) + (y/x+y) * (20) = k and if x < y, which of the following could be the value of k?
A. 10
B. 12
C. 15
D. 18
E. 30

OA - D
k=10(x+2Y)/x+y
The only values of x and y that cancel the 10 is 2 and 8.

This gives D answer.
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Re: Linear Equation

by dtweah » Tue May 05, 2009 10:07 am
crackgmat007 wrote:E. If x, y, and k are positive numbers such that (x/ y+x) * (10) + (y/x+y) * (20) = k and if x < y, which of the following could be the value of k?
A. 10
B. 12
C. 15
D. 18
E. 30

OA - D
K=10 (x+2y)/x+y

2+8 cancel the 10.
So D.
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by Ian Stewart » Tue May 05, 2009 11:11 am
Jose Ferreira and I offered three different ways to look at this question in this thread:

www.beatthegmat.com/two-questions-from- ... 34185.html
For online GMAT math tutoring, or to buy my higher-level Quant books and problem sets, contact me at ianstewartgmat at gmail.com

ianstewartgmat.com
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