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# M07-18

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Intern
Joined: 15 Nov 2016
Posts: 7
Schools: Kellogg '20 (S)

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11 Jul 2017, 14:31
IanStewart wrote:
josegf1987 wrote:
At least one is a Viper --> Couldn't there be two vipers - and therefore 0 cobras - and invalidate statement 1? Thanks.

In DS questions, you are never trying to 'invalidate' the statements. The statements are facts - they can't be wrong. You're trying to work out whether the question "how many cobras are there?" can have only one answer, or more than one answer.

If, when looking at one statement, you're considering a scenario that would make that statement false, you're considering a scenario that doesn't agree with the information you've been provided, so you're considering a scenario that isn't relevant to the problem.

Agreed not trying to invalidate statements - I was having a hard time understanding how (1) would still be sufficient in a scenario where we could have 0 cobras or 1 cobra in the box.

After giving the question another read, I see that it clearly states that "There is at least one viper and at least one cobra in Pandora's box".

It now makes sense.

Thank you
Intern
Joined: 28 Aug 2016
Posts: 16
GMAT 1: 560 Q44 V23

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22 Jul 2017, 06:32
I think this is a high-quality question and I agree with explanation.
Senior Manager
Joined: 28 Jun 2015
Posts: 274
Concentration: Finance
GPA: 3.5

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22 Jul 2017, 07:21
I just stumbled upon this question. Took me a while as to why S1 is the correct answer, but it was absurdly simple. Made me realise that I should start focusing more on the verbal section lol.

Nice one B.
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Intern
Joined: 18 Jun 2017
Posts: 9

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14 Aug 2017, 05:53
Hi Guys,

As per the question and S1:

There is at least one viper and at least one cobra in Pandora's box. How many cobras are there?
(1) From any two snakes from Pandora's box at least one is a viper.

it says that the box as at least one of the 2 snakes. So lets say the box has 10 vipes and 10 cobras = 20 snankes.
Now acc to S1 from any 2 snakes atleast one is a viper which means 1 or more than one, so in this case we can have 2 V and 0 C.

This would make the S1 insufficient.

Please let me know if my understanding of atleast 1 Viper is correct.

Ideally the question mentions only about the contents of the box so assuming there would be atleast 1 C in the box would be correct, but assuming the same for the 2 snakes would be wrong.

Please comment on this argument of mine.

Regards,
Abhishek
Math Expert
Joined: 02 Sep 2009
Posts: 61508

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14 Aug 2017, 06:19
salviabu wrote:
Hi Guys,

As per the question and S1:

There is at least one viper and at least one cobra in Pandora's box. How many cobras are there?
(1) From any two snakes from Pandora's box at least one is a viper.

it says that the box as at least one of the 2 snakes. So lets say the box has 10 vipes and 10 cobras = 20 snankes.
Now acc to S1 from any 2 snakes atleast one is a viper which means 1 or more than one, so in this case we can have 2 V and 0 C.

This would make the S1 insufficient.

Please let me know if my understanding of atleast 1 Viper is correct.

Ideally the question mentions only about the contents of the box so assuming there would be atleast 1 C in the box would be correct, but assuming the same for the 2 snakes would be wrong.

Please comment on this argument of mine.

Regards,
Abhishek

You'll benefit greatly if you read the whole discussion before posting a question. The second statement says: (1) From ANY two snakes from Pandora's box at least one is a viper.
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21 Aug 2017, 06:52
Oh! I got it!

Assuming that There are VVVVVVVVVV and (nC) in the box ; n is unknown number for now.

Whenever we pick any 2 snakes out of the box the possibility could be VV VC CV CC.

However, S1 tells us that "any 2 snakes taken out of the box will have at least 1 V"

and why is that? Because in the box C is less than 2 (n<2). Therefore, it is impossible to get CC.

Now let look back to the question states that "at least 1 C in the box" n>=1

Therefore 1<=n<2. The only answer here is 1 !!
Manager
Joined: 07 Jun 2017
Posts: 100

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22 Aug 2017, 05:08
Avigano wrote:
Took me some time to get this, it's a good question.
1) FROM ANY 2 SNAKES AT LEAST 1 IS A VIPER.
>>> This means that if I have one cobra and 1 Viper I have sufficiency.
>>> What happens if I add a Cobra? So now have 2 Cobras and 1 Viper. Here it's where it gets tricky, because the question is not testing proportions, it's testing logical deduction. I have 2 cobras and 1 Viper now, if I decide to pull out 2 snakes from pandora, I can get 1 Viper and 1 Cobra OR 2 Cobras. If I get 2 Cobras I'm not only dead but I'm also not respecting the condition that AT LEAST ONE IS A VIPER.

this really helps me ..
I try to get this statement for for an hour.
Intern
Joined: 04 May 2017
Posts: 1
Location: United States
Concentration: Human Resources, Organizational Behavior

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12 Sep 2017, 10:39
Hi Bunnel,

That's a wonderful question on logic. Kudos to you!
I got carried away thinking no where in the question it is mentioned that there are no other snakes in the box other than Cobras and Vipers. I was not convinced even after reading the explanation. But then realized that statement one holds true only when all but one snake are Vipers, how many types of snakes doesn't even matter. A good learning! Thanks for the question
Intern
Joined: 14 Sep 2017
Posts: 3

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15 Sep 2017, 05:25
I think this is a high-quality question and I agree with explanation. Explanation provided by AdmitJA made me "get" it!

This is actually a perfect 700 question. Looks deceptively easy and at first glance, seems contrary to common sense.
Intern
Joined: 21 Mar 2017
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GMAT 1: 680 Q45 V38
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26 Sep 2017, 05:12
i am happy with statement 2 being insufficient.

so are we saying that there are 98 vipers and 1 viper?
IIMA, IIMC School Moderator
Joined: 04 Sep 2016
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Location: India
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03 Dec 2017, 17:06
Bunuel niks18 chetan2u

I believe this this a value Q, we need to find unique answer to: how many cobras are there in a box?

Quote:
(1) Statement 1 tells us that from any two snakes from Pandora's box at least one is a viper. This may mean 1 cobra and 1 viper or 1 cobra and 99 vipers. Make sure you understand this distinction. S1 tells us that there is only 1 cobra in the box, which is sufficient.

If I got by AdmitJA logic,
Quote:
Statement 1: Any 2 snakes, possibilities ---> V, V or V, C or C, V.

I am getting zero cobra for first possibility and 1 cobra for second and third possibility.
Do we not need to have an unique answer to value Q?
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03 Dec 2017, 19:44
Bunuel niks18 chetan2u

I believe this this a value Q, we need to find unique answer to: how many cobras are there in a box?

Quote:
(1) Statement 1 tells us that from any two snakes from Pandora's box at least one is a viper. This may mean 1 cobra and 1 viper or 1 cobra and 99 vipers. Make sure you understand this distinction. S1 tells us that there is only 1 cobra in the box, which is sufficient.

If I got by AdmitJA logic,
Quote:
Statement 1: Any 2 snakes, possibilities ---> V, V or V, C or C, V.

I am getting zero cobra for first possibility and 1 cobra for second and third possibility.
Do we not need to have an unique answer to value Q?

What that user means that if from ANY two snakes from Pandora's box at least one is a viper, THESE two picked snakes (out of more than two from the box) could be VV, VC ot CV but NOT CC. It does NOT mean that there are 0 cobras. From (1) it follow that here is only 1 cobra in the box.
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16 Dec 2017, 08:26
My Take :

Statement 1:

It means there is at least 1 viper if we select any two.

So Viper count can be 1 or 2.But Cobra count cannot be 2 if we select any two.
This basically means there is only 1 Cobra.

In terms of scripts.
VC
CV
VV

But CC combination will not be possible.

Statement 2:
There are total of 99 snakes .The number of cobras not known.
So insufficient.

Kudos if it helps!!
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Joined: 23 Jan 2017
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25 Dec 2017, 01:56
I think this is a high-quality question and I agree with explanation.
Intern
Joined: 29 Sep 2017
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25 Feb 2018, 19:54
I think this is a high-quality question and I agree with explanation.
Intern
Joined: 07 Feb 2017
Posts: 7
Location: India
GPA: 4
WE: Sales (Manufacturing)

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15 Apr 2018, 07:41
I think this is a poor-quality question and the explanation isn't clear enough, please elaborate. Statements in question are ambigious. To ans DS question statements must be clear.
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Joined: 02 Sep 2009
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15 Apr 2018, 08:15
Fighter28 wrote:
I think this is a poor-quality question and the explanation isn't clear enough, please elaborate. Statements in question are ambigious. To ans DS question statements must be clear.

This question has 5 pages of discussion. That's because it's very hard. But let me assure you: the question is 100% GMAT like, unambiguous and mathematically correct. All I can suggest is to go through the discussion and read it carefully.
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Joined: 17 Jan 2017
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16 Apr 2018, 09:11
Fighter28 wrote:
I think this is a poor-quality question and the explanation isn't clear enough, please elaborate. Statements in question are ambigious. To ans DS question statements must be clear.

Took me a couple of minutes to get it. It helped me to think about it as a probability question:
There is at least one viper and at least one cobra in Pandora's box. How many cobras are there?

(1) From any two snakes from Pandora's box at least one is a viper.
Rephrase this statement to:
You grab 2 snakes out of the box (without replacing the first snake).
The probability of grabbing two cobras is zero.
==> only one cobra in the box

Great question B!!
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31 May 2018, 17:00
I think this is a poor-quality question and I agree with explanation. Statement 1 uses ambiguous language
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31 May 2018, 22:16
dabaobao wrote:
I think this is a poor-quality question and I agree with explanation. Statement 1 uses ambiguous language

The first statement is logically, mathematically and verbally 100% correct.
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Re: M07-18   [#permalink] 31 May 2018, 22:16

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# M07-18

Moderators: chetan2u, Bunuel