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At a certain college there are twice as many

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DennaMueller
 Post subject: At a certain college there are twice as many
 Post Posted: Mon Jul 20, 2009 9:15 pm 
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Course Students


Posts: 15
At a certain college there are twice as many english majors as history majors and three times as many english majors as mathematics majors. What is the ratio of the number of history majors to the number of mathematics majors?

    6 to 1
    3 to 2
    2 to 3
    1 to 5
    1 to 6

I set the problem up (incorrectly):
E=2h
E=3m
Therefor 2h:3m
But the answer is 3 to 2

What am I doing wrong?
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mxs2009
 Post subject: Re: At a certain college there are twice as many
 Post Posted: Tue Jul 21, 2009 1:49 am 
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Students


Posts: 16
Actually, everything is correct until the last part.

We know that 2h=3m, and we want to solve for h/m

h/m = 3/2. Thus, the ratio is 3:2
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RonPurewal
 Post subject: Re: At a certain college there are twice as many
 Post Posted: Tue Jul 21, 2009 7:48 pm 
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ManhattanGMAT Staff


Posts: 7146
easiest way to do this problem is to PLUG IN NUMBERS, because there are no definite quantities in the problem (all you have is ratios).

it's probably easiest to pick the number of english majors first, since that quantity is in both parts of the problem.
since that number is 3 times one quantity and 2 times another quantity, you can pick 6.

the first sentence then tells you that there are 3 history majors.
the second sentence tells you that there are 2 mathematics majors.
therefore, the desired ratio is 3:2.
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DennaMueller
 Post subject: Re: At a certain college there are twice as many
 Post Posted: Tue Jul 21, 2009 11:18 pm 
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Course Students


Posts: 15
mxs2009 wrote:
Actually, everything is correct until the last part.

We know that 2h=3m, and we want to solve for h/m

h/m = 3/2. Thus, the ratio is 3:2


This makes perfect sense. Thanks!
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Ben Ku
 Post subject: Re: At a certain college there are twice as many
 Post Posted: Tue Aug 18, 2009 5:21 pm 
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ManhattanGMAT Staff


Posts: 823
Glad this was helpful. You can either use a "plug in numbers" approach suggested by Ron, or to combine the ratios approach that you attempted. The key is that you look for the right thing. "Ratio of history to math" means "What is H:M?"

Let me know if there are additional questions. Thanks!

_________________
Ben Ku
Instructor
ManhattanGMAT
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sureng.reddy
 Post subject: Re: At a certain college there are twice as many
 Post Posted: Wed Feb 03, 2010 12:39 pm 
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Course Students


Posts: 6
I got confused with "At a certain college there are twice as many english majors as history majors"
as 1 H = 2 E ; H->History and E -> English

Isn't it confusing?
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RonPurewal
 Post subject: Re: At a certain college there are twice as many
 Post Posted: Mon Mar 08, 2010 7:28 am 
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ManhattanGMAT Staff


Posts: 7146
sureng.reddy wrote:
I got confused with "At a certain college there are twice as many english majors as history majors"
as 1 H = 2 E ; H->History and E -> English

Isn't it confusing?


this is an example of a math problem on which language barriers pose a non-negligible difficulty. while language barriers are clearly less of an issue than on the verbal section, they are sometimes problematic on the math section as well.

for a lifelong native speaker of english, this sentence would pose no confusion whatsoever. for a non-native speaker of the language, however, this sentence gives an important TAKEAWAY: if you see "there are twice as many X as Y", then this means the number of X is twice the number of Y.

memorize it! put it on a flash card!
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