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Re: In a group of 30 students, 8 are enrolled in an English [#permalink]
ggarr, you said 7 are enrolled in both the classes, means these 7 students should belong to the numbers given for both classes i.e. 16+8=24. If yes, then what justifies 20 students taking only one class which also come from 16+8= 24 ?
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Re: In a group of 30 students, 8 are enrolled in an English [#permalink]
somethingbetter wrote:
In a group of 30 students, 8 are enrolled in an English class and 16 are enrolled in an Algebra class. How many students are enrolled in both an English and an Algebra class?

(1) 20 are enrolled in exactly one of these two classes.

(2) 3 are not enrolled in either of these classes.

I think I was careless the first time around. This is my second go.
Stem: 24 are enrolled in E, A or E and A. 6 are in neither.
1) if 20 are in A or E and 6 are in neither then 4 are in both
2) 30 students in total, 24 are enrolled in E, A or E and A and 3 are in neither. 30 - 3 = 27 students in E, A or E and A. insufficient and inconsistent

now I'm getting A. hmmmm

Originally posted by ggarr on 31 Aug 2007, 13:37.
Last edited by ggarr on 31 Aug 2007, 14:35, edited 3 times in total.
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Re: In a group of 30 students, 8 are enrolled in an English [#permalink]
somethingbetter wrote:
ggarr, you said 7 are enrolled in both the classes, means these 7 students should belong to the numbers given for both classes i.e. 16+8=24. If yes, then what justifies 20 students taking only one class which also come from 16+8= 24 ?
I completely overlooked the 16+8=24 part. please ignore that post.
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Re: In a group of 30 students, 8 are enrolled in an English [#permalink]
Still, OA is D , my friend.:(
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Re: In a group of 30 students, 8 are enrolled in an English [#permalink]
somethingbetter wrote:
In a group of 30 students, 8 are enrolled in an English class and 16 are enrolled in an Algebra class. How many students are enrolled in both an English and an Algebra class?

(1) 20 are enrolled in exactly one of these two classes.

(2) 3 are not enrolled in either of these classes.



To find how many students are enrolled in both we can use any of the following two formulas:

Both=ENG+ALG+none-Total
or
Both=Total-(ENG(only)+ALG(only))-none

Let`s plug in what is given in the question, we get;

Both=8+16+none-30
or
Both=30-(ENG(only)+ALG(only))-none, these are the formulas we have;

1st- gives us (ENG(only)+ALG(only)), insuf, still need the # of none
2nd- gives #none- suff

So, my answer is B

Originally posted by IrinaOK on 31 Aug 2007, 14:21.
Last edited by IrinaOK on 31 Aug 2007, 14:44, edited 2 times in total.
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Re: In a group of 30 students, 8 are enrolled in an English [#permalink]
somethingbetter wrote:
In a group of 30 students, 8 are enrolled in an English class and 16 are enrolled in an Algebra class. How many students are enrolled in both an English and an Algebra class?

(1) 20 are enrolled in exactly one of these two classes.

(2) 3 are not enrolled in either of these classes.


Set x=students who take both Algebra and English, Venn Diagram formula gives:
16 + 8 - x + neither = 30
-x + neither = 6
We are trying to find x

(1) Knowing that students taking exactly one class = 20, you can obtain:
20 + x + neither = 30
x + neither = 10
Using equation above, you can solve for "neither":
2*neither = 16
neither = 8
Plug this in, you should get x = 2
SUFFICIENT

(2) Neither = 3
Plug in, you get x = -9!!!
I would say it is sufficient, but neither = 3 doesn't make any sense. Think about it. If you have total of 30 students, 3 doesn't take any class, you have 27 students total taking English, Algebra, or both. This number should be no more than (16+8 =) 24. This is impossible.
I would say SUFFICIENT, but bad given number.

Originally posted by bkk145 on 31 Aug 2007, 14:32.
Last edited by bkk145 on 31 Aug 2007, 14:34, edited 1 time in total.
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Re: In a group of 30 students, 8 are enrolled in an English [#permalink]
Explain please. I guess, it's E
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Re: In a group of 30 students, 8 are enrolled in an English [#permalink]
bkk145 wrote:
somethingbetter wrote:
In a group of 30 students, 8 are enrolled in an English class and 16 are enrolled in an Algebra class. How many students are enrolled in both an English and an Algebra class?

(1) 20 are enrolled in exactly one of these two classes.

(2) 3 are not enrolled in either of these classes.


Set x=students who take both Algebra and English, Venn Diagram formula gives:
16 + 8 - x + neither = 30
-x + neither = 6
We are trying to find x

(1) Knowing that students taking exactly one class = 20, you can obtain:
20 + x + neither = 30
x + neither = 10
Using equation above, you can solve for "neither":
2*neither = 16
neither = 8
Plug this in, you should get x = 2
SUFFICIENT

(2) Neither = 3
Plug in, you get x = -9!!!
I would say it is sufficient, but neither = 3 doesn't make any sense. Think about it. If you have total of 30 students, 3 doesn't take any class, you have 27 students total taking English, Algebra, or both. This number should be no more than (16+8 =) 24. This is impossible.
I would say SUFFICIENT, but bad given number.


Yes, agree A.

I forgot about second equation. Given two equation we can find two unknow variables.

Thank you!

Though probably OA is D, assuming we do not calculate...
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Re: In a group of 30 students, 8 are enrolled in an English [#permalink]
I do agree with bkk145,
1) is sufficient and it is proven
2) is sufficient to find an ANSWER to the problem even if it is -3 persons who take both subjects

So the answer is D



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