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freshman high school class

by himu » Sun Mar 17, 2013 5:39 am
In a freshman high school class there are 125 total students. If 75 of the total students are enrolled in Geometry, how many of those students are enrolled in Biology?

50 of the total students are enrolled in Geometry but not Biology.

The number of those students who are enrolled in Geometry and Biology is the same as the number of those students enrolled in neither Geometry nor Biology.
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by Anju@Gurome » Sun Mar 17, 2013 6:06 am
himu wrote:In a freshman high school class there are 125 total students. If 75 of the total students are enrolled in Geometry, how many of those students are enrolled in Biology?

(1) 50 of the total students are enrolled in Geometry but not Biology.
(2) The number of those students who are enrolled in Geometry and Biology is the same as the number of those students enrolled in neither Geometry nor Biology.
Let us assume the numbers of students enrolled in Geometry, Biology, both, and none are G, B, O, and N, respectively.
Hence, (G + B - O + N) = 125 and G = 75
We need to find O.

Statement 1: (G - O) = 50 ---> O = 25

Sufficient

Statement 2: O = N

Not sufficient

The correct answer is A.
Last edited by Anju@Gurome on Mon Mar 18, 2013 4:23 am, edited 1 time in total.
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by himu » Mon Mar 18, 2013 4:12 am
Hey Anju,

Thank for your time on this.
BUt I have teh following doubt:

What is the Q asking ?
--> If 75 of the total students are enrolled in Geometry, how many of those students are enrolled in Biology?
So how many of those what does those refer to ? What I infer is, it refers to those students out of 75 who are enrolled in Biology?

so the ones who are common.

SO my ans is A.

Also, as per your explanation :

et us assume the numbers of students enrolled in Geometry, Biology, both, and none are G, B, O, and N, respectively.
Hence, (G + B - O + N) = 125 and G = 75
Hence, B = (125 - G + O - N) = (50 + O - N)

Statement 1: (G - O) = 50 ---> O = 25
Still we don't know N.

we have to find O ...why N ? N is none of the students taking B or G.

Pls correct me if I am wrong.


Thanks & Regards,
~Himu.
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by Anju@Gurome » Mon Mar 18, 2013 5:08 am
himu wrote:So how many of those what does those refer to ? What I infer is, it refers to those students out of 75 who are enrolled in Biology?
That's correct I think.
If the problem meant what I was interpreting, it should have mentioned "..how many of the total students are enrolled for Biology?"

Thanks for pointing it out.
I've edited my reply.
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by Brent@GMATPrepNow » Mon Mar 18, 2013 5:13 am
I think the question could be worded differently to avoid any confusion.
Full disclosure: I first read it as "What is the total number of students taking Biology?" However, upon rereading it, the question does seem to be asking for the number of students taking both Biology and Geometry.

Cheers,
Brent
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