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DS question - need help

by sjcl1526 » Sat Jun 01, 2013 12:35 pm
Hi - I am unable to get this question right especially on S1 and S1.Could anyone help me with this. Thank you!


At a certain wedding, the bar served only beer and wine. If 320 people attended the wedding and 200 attendees drank wine, how many attendees drank neither beer nor wine?

(1) There were the same number of beer drinkers as nondrinkers.

(2) The same number of people drank only beer as drank both beer and wine.

Statement (1) ALONE is sufficient, but statement (2) alone is not sufficient to answer the question asked

Statement (2) ALONE is sufficient, but statement (1) alone is not sufficient to answer the question asked

Both statements (1) and (2) TOGETHER are sufficient to answer the question asked; but NEITHER statement ALONE is sufficient

EACH statement ALONE is sufficient to answer the question asked

Statements (1) and (2) TOGETHER are NOT sufficient to answer the question asked, and additional data specific to the problem are needed
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Source: — Data Sufficiency |
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by srcc25anu » Sat Jun 01, 2013 12:46 pm
we know total wine drinkers = 200
so total NOT WINE drinkers = 320-200 = 120
ST1: Same no of beer drinkers as non drinkers
so Total # of Beer Drinkers = 320/2 = 160
and Total Not BEER drinkers = 160
This does not lead us to how many drank neither because we don't know how many of the Total BEER drinkers also drank wine or who only drank beer.
Not sufficient
St2: Only Beer drinkers = Beer + Wine Drinkers
so # who drink Beer but Not Wine = 0
hence who drink neither = 120 - 0 = 120
SUFFICIENT

IMO B
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by sjcl1526 » Sun Jun 02, 2013 6:39 am
How is this? I did not get this right.

Total # of Beer Drinkers = 320/2 = 160
and Total Not BEER drinkers = 160
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by faraz_jeddah » Wed Jun 05, 2013 2:10 am
srcc25anu wrote:we know total wine drinkers = 200
so total NOT WINE drinkers = 320-200 = 120
ST1: Same no of beer drinkers as non drinkers
so Total # of Beer Drinkers = 320/2 = 160
and Total Not BEER drinkers = 160
This does not lead us to how many drank neither because we don't know how many of the Total BEER drinkers also drank wine or who only drank beer.
Not sufficient
St2: Only Beer drinkers = Beer + Wine Drinkers
so # who drink Beer but Not Wine = 0
hence who drink neither = 120 - 0 = 120
SUFFICIENT

IMO B
I think C is the Answer.

We both agree (1) is not suff.

So lets attack (2)
Only beer drinkers = BxNW
Beer and Wine = BxW
I have marked your mistake srcc25anu in red.

W NW
B x x = 2x
NB ? ? = ?
Total 200 120 = 320

There is no way you can find NBxNW
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by Atekihcan » Wed Jun 05, 2013 3:57 am
Total (T) = Beer (B) + Wine (W) - Both (H) + None (N)
We need to determine N.

Now, T = 320 and W = 200

So, 320 = B + 200 - H + N
So, N = 320 - (B + 200 - H) = 120 - B + H

Statement 1: B = N
So, N = 120 - N + H
So, 2N = 120 + H

As we don't know H, we cannot determine N.
So, statement 1 is not sufficient.

Statement 2: Only beer = (B - H) = H
So, 2H = B
So, N = 120 - B + H
So, N = 120 - H

As we don't know H, we cannot determine N.
So, statement 2 is not sufficient.

Both statements together: 3N = 240
So, N = 80

So, both statements together is sufficient.

Answer : C
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by ceilidh.erickson » Fri Jun 07, 2013 12:55 pm
I find that the best way to approach these Overlapping Sets problems is to set up a matrix:

Image

Now plug in the information from the first statement.

Image

Even if we carry all of the information through and create relationships, we can't get to a value for x:

Image

When we evaluate statement 2, we need to erase the information from statement 1 and consider it on its own:

Image

Again, we don't have enough information to get to a value for y, so we can't solve.

If we put the statements together, though, then we have enough information to solve for a value:

Image

The answer is C.
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by ceilidh.erickson » Fri Jun 07, 2013 12:57 pm
For more on overlapping sets, see here: https://www.beatthegmat.com/survery-resu ... tml#576105
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by GaneshMalkar » Sun Jun 09, 2013 4:55 am
Atekihcan wrote:Total (T) = Beer (B) + Wine (W) - Both (H) + None (N)
We need to determine N.

Now, T = 320 and W = 200

So, 320 = B + 200 - H + N
So, N = 320 - (B + 200 - H) = 120 - B + H

Statement 1: B = N
So, N = 120 - N + H
So, 2N = 120 + H

As we don't know H, we cannot determine N.
So, statement 1 is not sufficient.

Statement 2: Only beer = (B - H) = H
So, 2H = B
So, N = 120 - B + H
So, N = 120 - H

As we don't know H, we cannot determine N.
So, statement 2 is not sufficient.

Both statements together: 3N = 240
So, N = 80

So, both statements together is sufficient.

Answer : C

I may be wrong in my understanding but the Question says "drank wine". So the bold above W = 200 shouldn't be W + B = 200; Since drank wine I interpreted as "not only Wine".
If you cant explain it simply you dont understand it well enough!!!
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