31-#36

This topic has expert replies
Source: — Problem Solving |

Master | Next Rank: 500 Posts
Posts: 214
Joined: Fri Jul 20, 2007 1:35 am
Thanked: 3 times

by beny » Sun Aug 19, 2007 5:02 pm
B. 12 --> i.e. x=2, y=3.

Both fractional terms are equal. The first term would constitute 1/3 of k, the second term would constitute 2/3 of k.

B: k=12, therefore (x/(x+y))*10 = 4, (x/(x+y))*20 = 8.
Therefore, x=4, x+y=10, y=6

A: can't work because 10 is not divisible by 3.
C: can't work because both fractional terms have to equal 1/2 (which only works when x=y)
D: can't work because 1/2 of k would be 6, 2/3 of k would be 12.
(x/(x+y))*10=6, (x/(x+y))*20=12
Therefore, x=6, x+y=10, y=4, and x>y (which violates the rule)
E: can't work because both fractional terms have to equal 1 (which is impossible since x<y, so y can't=0; if x=0, the entire fraction equals 0.)

User avatar
Master | Next Rank: 500 Posts
Posts: 277
Joined: Sun Jun 17, 2007 2:51 pm
Location: New York, NY
Thanked: 6 times
Followed by:1 members

by givemeanid » Sun Aug 19, 2007 5:58 pm
x = 1, y =4, k = 18. Answer is D.
So It Goes

Master | Next Rank: 500 Posts
Posts: 214
Joined: Fri Jul 20, 2007 1:35 am
Thanked: 3 times

by beny » Sun Aug 19, 2007 6:25 pm
givemeanid wrote:x = 1, y =4, k = 18. Answer is D.
Umm.. x=1, y=4, k=6....

Answer is B.

Master | Next Rank: 500 Posts
Posts: 484
Joined: Sun Jul 30, 2006 7:01 pm
Thanked: 2 times
Followed by:1 members

by magical cook » Mon Aug 20, 2007 8:52 am
Thanks for the response! the answer is D) :)

Master | Next Rank: 500 Posts
Posts: 214
Joined: Fri Jul 20, 2007 1:35 am
Thanked: 3 times

by beny » Mon Aug 20, 2007 9:03 am
How is the answer D? What's the OE?

User avatar
Master | Next Rank: 500 Posts
Posts: 277
Joined: Sun Jun 17, 2007 2:51 pm
Location: New York, NY
Thanked: 6 times
Followed by:1 members

by givemeanid » Mon Aug 20, 2007 9:43 am
(x/x+y)*10 + (y/x+y)*20 = k
10(x+2y) = k(x+y)
Since x and y are +ve and x < y, k > 10.

Lets start with Choice C.
10(x+2y) = 15(x+y)
5y = 5x
Since x < y, this value of k is not big enough.

Try D.
10(x+2y) = 18(x+y)
2y = 8x
y = 4x
CORRECT.


You can also verify other choices and see that they do not hold up.
So It Goes

Master | Next Rank: 500 Posts
Posts: 214
Joined: Fri Jul 20, 2007 1:35 am
Thanked: 3 times

by beny » Mon Aug 20, 2007 10:16 am
Oh... it's a y in the second numerator.. my b, kept reading both fractions with x in num.

User avatar
GMAT Instructor
Posts: 613
Joined: Thu Mar 22, 2007 6:17 am
Location: madrid
Thanked: 171 times
Followed by:64 members
GMAT Score:790

by kevincanspain » Sat Aug 25, 2007 9:50 am
Candidates from the US apply to an average of 20 B-schools each, whereas candiates from outside the US apply to an average of 10 B- schools each. Which of the following could be the average number of B- schools that candiates (American and otherwise) apply to if US candiates outnumber foreign candidates?

This would have been an easier way to rephrase the same question!
Kevin Armstrong
GMAT Instructor
Gmatclasses
Madrid