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students at college C

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students at college C

by pepeprepa » Sat Aug 23, 2008 3:11 pm
If 2/5 of the students at College C are business majors, what is the number of female students at college C?
1) 2/5 of the male students at College C are business majors
2) 200 of the female students at College C are business majors
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by II » Sat Aug 23, 2008 5:00 pm
With these types of questions, I find it really helps to draw out a chart to organise the information, and be able to clearly see what information is required in order to answer the question.

See attached chart.

The text in black bold is the information from the question stem.
The text in blue is the information from Statement 1.
The text in red is the information from Statement 2.

From this we can clearly see that we dont have enough information to find the number of Females.

Choose E.
Attachments
info org chart btg.jpg
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by ebehboud » Sat Aug 23, 2008 9:00 pm
I have a different view.

From the question..
2/5(F+M) = B

(1): 2/5M=B using this with the question formula..
We can solve for F in terms of B...
Yet.. this isn't sufficient to determine F... 2/3F = B

(2) 200 of females in B... doesn't say anything about the total population.

1&2: 2/3F = B,,,,, and 200 of F= B.. => 2/3F = 200 and F= 300

my pick is C
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by BILL » Sat Aug 23, 2008 11:43 pm
definitely E...

Both are cleary insuff individually, but together they still dont tell you how many males students there are or what % of the female population are business majors.

If you knew one or the other you'd be able to solve.
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by pepeprepa » Sun Aug 24, 2008 12:53 am
OA is C
If some pople can provide full explanation and comparative questions, it would be nice.
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by II » Sun Aug 24, 2008 2:07 am
ebehboud wrote:I have a different view.

From the question..
2/5(F+M) = B

(1): 2/5M=B using this with the question formula..
We can solve for F in terms of B...
Yet.. this isn't sufficient to determine F... 2/3F = B

(2) 200 of females in B... doesn't say anything about the total population.

1&2: 2/3F = B,,,,, and 200 of F= B.. => 2/3F = 200 and F= 300

my pick is C
Can you provide more information here.
Especially with statement 1.
How did you get from 2/5m=B to 2/3F=B ???

Thanks.
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Re: students at college C

by sudhir3127 » Sun Aug 24, 2008 2:51 am
pepeprepa wrote:If 2/5 of the students at College C are business majors, what is the number of female students at college C?
1) 2/5 of the male students at College C are business majors
2) 200 of the female students at College C are business majors
I go with C as well

Assume male students =X
Female students = y

total Biz majors = (2/5)(X+y)
non-Biz majors =(1- 2/5)(X+Y) = (3/5)(x+y)

statement 1: 2/5 of males students are business majors ..which means 3/5 of male students are non-business majors
= 3X/5
non-biz females=(3/5)(X+Y)-3X/5=(3/5)Y

no information on actual number of students

not sufficient

statement 2: 200 female students are business majors.

no information on non-biz majors female students

not sufficient

statement 1&2: 3/5 of male students are non-biz majors and 200 female students are biz majors
non-biz females= (3/5)Y
biz females = Y-(3/5)Y=(2/5)Y
(2/5)Y=200
=>Y=500
thus females are 500


sufficient

Hence C

hope this helps... i have actually done in a very exhaustive manner..looks like>2 mints..but its just to understand the concept... other wise..it will not take more than a minute/half...

PS: I am sure 2/3 is a typo..
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by pepeprepa » Sun Aug 24, 2008 3:50 am
I went for B during the test because my error was this:
2/5(M+F)=number of business majors
2/5M + 2/5F=number of business majors
And so 200=2/5F

But we cannot go from the first to the second line because the total proportion is not equal to the same proportion of F + the same porportion of M. That's good sens for some people I think, it was not for me, so hope it helps someone if he makes the same error.

You can simply understand it with a counter-example!
If M=100 and F=200
We have 2/5*300=120

We could have 100% of M and 10% of F
100/100*100 + 1/10*200=120
or
20% of M and 50% of F
20/100*100 + 50/100*200=120

Thanks to all responders
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by yogesh garg » Sun Jan 02, 2011 10:34 am
Image
[/list]
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by tomada » Sun Jan 02, 2011 3:26 pm
Nicely done, Sudhir!

sudhir3127 wrote:
pepeprepa wrote:If 2/5 of the students at College C are business majors, what is the number of female students at college C?
1) 2/5 of the male students at College C are business majors
2) 200 of the female students at College C are business majors
I go with C as well

Assume male students =X
Female students = y

total Biz majors = (2/5)(X+y)
non-Biz majors =(1- 2/5)(X+Y) = (3/5)(x+y)

statement 1: 2/5 of males students are business majors ..which means 3/5 of male students are non-business majors
= 3X/5
non-biz females=(3/5)(X+Y)-3X/5=(3/5)Y

no information on actual number of students

not sufficient

statement 2: 200 female students are business majors.

no information on non-biz majors female students

not sufficient

statement 1&2: 3/5 of male students are non-biz majors and 200 female students are biz majors
non-biz females= (3/5)Y
biz females = Y-(3/5)Y=(2/5)Y
(2/5)Y=200
=>Y=500
thus females are 500


sufficient

Hence C

hope this helps... i have actually done in a very exhaustive manner..looks like>2 mints..but its just to understand the concept... other wise..it will not take more than a minute/half...

PS: I am sure 2/3 is a typo..
I'm really old, but I'll never be too old to become more educated.
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by tanviet » Thu Aug 11, 2011 7:06 pm
VERY HARD AND TRICKY FROM GMATPREP.

gmatprep contains very hard questions which are tricky not require advanced level hard math or formular

Using table, I first choose E. Using table is normal for this kind of questions

However use argument is better.

2/5 of student is business major and 2/5 of male is business major. So, 2/5 of female must be business major. 2/5 of female is 200. So female is 500
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by tanviet » Thu Aug 11, 2011 7:22 pm
NEVER UNDERESTIMATE gmatprep questions.

we can make more clear by drawing like this

--------- ---------- ---------




---------2/5 ---------- 2/5 ---------2/5

--------- ---------- ---------
male female total
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by GmatKiss » Fri Aug 12, 2011 12:49 am
IMO:C
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