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M27-03

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Re: M27-03  [#permalink]

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New post 08 Jan 2017, 05:57
manisharora wrote:
Hi Bunuel,
I am getting confused while trying to understand how the count for total acrophobia which as per your solution is equal to 58-45=13? I think the following should be the correct case:- Total number of patients - No Arachnophobia = Acrophobia+ Neither of the two.


Please re-read the solution. From (1) Total = 58 and No acrophobia = 45, thus (acrophobia) = (total) - (no acrophobia) = 58 - 45 = 13.

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New post 28 Jan 2017, 22:18
MaMa77 wrote:
Hi Bunuel,
I am getting confused while trying to understand how the count for total acrophobia which as per your solution is equal to 58-45=13? I think the following should be the correct case:- Total number of patients - No Arachnophobia = Acrophobia+ Neither of the two.


Hope this clarifies.
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New post 30 Apr 2018, 14:36
How could we assume 58 is the total number of patients in Vertigo Hospital? Shouldn't it be "Of all the 58 patients of Vertigo Hospital"?
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New post 25 May 2018, 14:17
Canteenbottle wrote:
How could we assume 58 is the total number of patients in Vertigo Hospital? Shouldn't it be "Of all the 58 patients of Vertigo Hospital"?


The stem says "Of the 58 patients of Vertigo Hospital" which is the same as "there are 58 patients in the Vertigo hospital". (Must be a very tall building to have vertigo in its name...)

My solution:

Formula for overlapping venn diagram with 2 variables is simply as follows:

(Circle 1 - overlap) + overlap + (circle 2 - overlap) + Neither = total

Here it tells you that neither is the same as overlap.

Hence:
Circle 1 - overlap + overlap + circle 2 - overlap + overlap = total --> all overlaps cancel out --> 58 - 45 = 13 --> A is sufficient.
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New post 19 Jun 2018, 11:56
1
How do we figure out that a particular question can be solved only by a double- set matrix and not by a venn diagram?

Because if we do it by a diagram, waste 2 minutes, and then resolve to do it by a double set matrix, it will take A LOT of time

Or should we solve all questions involving two variables (eg physics and chemistry) with a double set matrix only?
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New post 11 Sep 2018, 09:33
It’s simple : total-( neither of Ar and Ac ) = Ar+Ac-(common of Ar and Ac)
So here T= 58
(Neither of Ar and Ac)=common of Ar and Ac

Ar= 46 ,so Ac = 58-45= 13 hence 1 is sufficient

2 is not sufficient as neither of Ar and Ac is unknown

So answer is A
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New post 20 Sep 2018, 13:38
Total number of patients of vertigo hospital = 58
Number of patients with arachnophobia = 45
Number of patients with acrophobia = y

From (1)

Number of patients with both arachnophobia and acrophobia =x

Number of patients with neither arachnophobia nor acrophobia =x

Number of patients with only arachnophobia = 45-x

Number of patients with only acrophobia = y-x

Using the formula : 58 =(45-x) +(y-x) + x + x
58 = 45 + y
y =58-45 =13
this is sufficient.

From (2)
We are only given the number of patients with only arachnophobia which is insufficient to determine the solution.
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New post 30 Sep 2018, 12:13
I think it a good question that requires concentration.
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New post 23 Oct 2018, 10:56
shasadou wrote:
I think this is a poor-quality question. guyes u need to reconfigure your overlappins problems. they are misleading. i ve noted in my posts somewhere that you are inconsistent in logic: in overlapping sets you leave the room for assumptions, in other type of questions you dont.



On the contrary i think its a really good Q.. It took me a lot of time to believe this..Took me until i Figured out my way..!! hope the below may help for statement A (Statement B is pretty straightforward i think)

Logically the only possibilities are 1) both 2) none 3) Only Acro 4) Only arachno

Let x be be equal to both which is also equal to none

Only Acro = total - (both+none+ Only Arachno)
= 58 - (x+x+45-x)
= 13-x

Total Acro = Only Acro + both
= 13-x+x
=13


To add to the above. You can take x as anything. Suppose 5 have both and 5 have none. Then only Acro will be 13-5 = 8 Plus the 5 (patients having both phobias). its compensating basically. If none increase by 1, the common set increase by 1 too so there is no net effect on Acro (which also takes into count patients having both phobia).
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New post 21 Nov 2018, 21:29
I agree with explanation.
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New post 02 Dec 2018, 10:32
I found this to be simple question:

Total = arachnophobia + acrophobia - Both + Neither.

As per statement I "Both" and "Neither" are equal so, 58 = 32 (arachnophobia) + acrophobia, therefore, acrophobia = 13.


As per statement II, we can find "both" but dont know anything about, "Neither", so Insufficient, (also, some might have a doubt that whether "Neither" i.e patients no illnesses exist, but statement I, states that Neither and both are equal, so neither category exists)
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New post 04 Mar 2019, 00:38
I think this is a high-quality question and I agree with explanation. One of the trickiest!
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New post 27 Mar 2019, 18:22
Are the sets not mutually exclusive?. One can have disease right? .

Can anyone solve it through Venn Diagram please
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New post 27 Mar 2019, 20:14
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New post 16 Jul 2019, 09:56
Hey Bunuel
When I get an overlap question, I am able to solve it using the formula which we have in our math book. Often, I make Venn diagrams to understand the question, but many a times, when the questions has a lot of details in it I have seen working through column-row structure is very easy.
For example this beautiful question (https://gmatclub.com/forum/of-three-per ... l#p2266227) that I tried a few days back from Quant Review 2020 was easy when you think it through a column-chart. I started this question with a Venn diagram only to get it incorrect even after 5 minutes of wondering. After reading Scotts reply, I was impressed. ScottTargetTestPrep

When would you suggest that we make a Venn diagram and when should we deal the question with a column-row chart structure. I just wanted to know and understand your perspective as it would be very helpful. In anticipation of your response.

Thanks
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