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# M07-18

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Math Expert
Joined: 02 Sep 2009
Posts: 59721

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21 Jan 2015, 01:04
i see the goal here (trickery), but the question wording is wrong.

Implication of "any" two snakes is that there are more than 1 pair, otherwise proper english would be "the" two snakes.

This one should be dumped from the question bank.

What;s wrong in assuming that there are more than 1 pair?
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Joined: 30 Nov 2013
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02 Mar 2015, 18:14
Excellent question, but I'm partial because I got it right.
It's more representative of the type of thinking on the verbal portion of the exam, IMO, which is another reason I like it, and it also reminded me of the Monty Hall problem for whatever reason.
Intern
Joined: 20 Apr 2015
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27 May 2015, 16:34
At least one is a Viper --> Couldn't there be two vipers - and therefore 0 cobras - and invalidate statement 1? Thanks.
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Joined: 08 Jun 2014
Posts: 12

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27 May 2015, 17:27
Look at the question. The condition u mentioned is out of scope. The question clearly says that there is atleast one V and one C in the box.
You should not consider the case where cobras are 0.

When only the condition in the question is considered

Possible cases are
1v 1c
2v 2c
Etc

Cases that are out of scope
1v 0c
2v 0c
3v 0c
.
.
.
Nv 0c
0v 1c
0v 2c
0v 3c
.
.
.
0v Nc
Intern
Joined: 29 Sep 2013
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10 Jun 2015, 19:55
Bunuel wrote:
KPMM07 wrote:
I think this question is poor and not helpful.

Please elaborate on this. The question is perfectly valid, though quite hard.

Interesting solution, but not sure how this is math (not counting/probability/algebra/arithmetic etc.)
More like it was a question testing your logical deduction.
Math Expert
Joined: 02 Sep 2009
Posts: 59721

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23 Sep 2015, 22:10
shavak wrote:
I think this is a poor-quality question and the explanation isn't clear enough, please elaborate.

You should specify what is unclear to you in the explanation. Also, reading the whole thread might help.

P.S. I think this is a prefect question.
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31 Oct 2015, 14:32
I think this is a high-quality question and I agree with explanation.
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Joined: 06 Sep 2015
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12 Dec 2015, 14:25
Definitely a difficult question, but it helped me to think of statement 1 in this way: "If you pick any two snakes, at least one is a viper".
So, what if there are 4 snakes, 2 cobras and 2 vipers? Pick two snakes.
You could get 1 cobra, 1 viper (which agrees with statement 1)
Or you could get 2 vipers (also agrees with statement 1)
Or you could get 2 cobras. This option DOES NOT agree with statement 1. So we know - that we cannot ever pick two cobras. The only way to ensure we never pick two cobras, given that there could be ANY NUMBER of snakes in the box, is if we only have ONE cobra.
Ex: 4 snakes, 3 viper, one cobra.
Pick two = 2 vipers, or 1 viper, 1 cobra.

Hope this helps!
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Joined: 01 Jul 2015
Posts: 1
Schools: Duke '20

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17 Dec 2015, 09:58
I don't agree with the explanation. As per GMAT both the statements should agree with each other. However here they are contradicting.
Math Expert
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Posts: 59721

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17 Dec 2015, 09:59
omi wrote:
I don't agree with the explanation. As per GMAT both the statements should agree with each other. However here they are contradicting.

How are the statements contradict each other? Can you please specify? Thank you.
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24 Dec 2015, 08:00
How can you know how many of any snakes are in the box if the total amount of snakes is not given?
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24 Dec 2015, 08:25
estei053 wrote:
How can you know how many of any snakes are in the box if the total amount of snakes is not given?

We need to know how many cobras are in the box. And the info given in (1) tells us that there must be exactly one cobra in the box.
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25 Dec 2015, 03:22
Very difficult question
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Joined: 07 Feb 2015
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27 Dec 2015, 19:04
Bunuel wrote:
SUMANMG wrote:
I think this is a poor-quality question and the explanation isn't clear enough, please elaborate. GMAC say, they do not contradict the data given in 2 sentences in the DS problems. But here it contradicts. Can you please explain?

Where do you see a contradiction? The question is hard but perfectly fine.

I got this question right but I also thought there was a contradiction which made me second guess myself since official GMAC policy is DS stimulus will not contradict each other.

Per (1) there could only be two snakes in the box, one being a cobra, one being a viper. Thus (1) is sufficient.

(2) contradicts (1) in saying that there are 99 snakes in the box.
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27 Dec 2015, 20:51
gmatser1 wrote:
Bunuel wrote:
SUMANMG wrote:
I think this is a poor-quality question and the explanation isn't clear enough, please elaborate. GMAC say, they do not contradict the data given in 2 sentences in the DS problems. But here it contradicts. Can you please explain?

Where do you see a contradiction? The question is hard but perfectly fine.

I got this question right but I also thought there was a contradiction which made me second guess myself since official GMAC policy is DS stimulus will not contradict each other.

Per (1) there could only be two snakes in the box, one being a cobra, one being a viper. Thus (1) is sufficient.

(2) contradicts (1) in saying that there are 99 snakes in the box.

The statements do NOT contradict each other:

The first statement implies that there must be exactly one cobra in the box. (2) says that there are 99 snakes. So, 1 cobra and 98 vipers.
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Location: United States
GMAT 1: 670 Q45 V38
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13 Feb 2016, 18:07
I thought this was a very challenging question that I got wrong, but after reading through everyone's explanations I now understand.

What most of (those who got it wrong) did was read over the original question, and then totally forget about it. There has to be @ least 1 cobra, and @ least one viper.
Current Student
Joined: 12 Nov 2015
Posts: 55
Location: Uruguay
Concentration: General Management
Schools: Goizueta '19 (A)
GMAT 1: 610 Q41 V32
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21 Feb 2016, 10:48
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.
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GMAT 1: 770 Q50 V47
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28 Mar 2016, 18:15
I think this is a poor-quality question and I agree with explanation. The natural interpretation of "for every x of this there is y of this" is that there is a minimum ratio
Math Expert
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Posts: 59721

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28 Mar 2016, 22:17
tblefevre wrote:
I think this is a poor-quality question and I agree with explanation. The natural interpretation of "for every x of this there is y of this" is that there is a minimum ratio

Can you please elaborate what you mean?
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WE: Information Technology (Computer Software)

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21 Apr 2016, 19:51
I think this is a high-quality question and I don't agree with the explanation. hi, the question tells us that there is 1 viper & 1 snakes per box. So, the question asks how many cobras are there. this means that the question is asking to find out the total no of cobras. Isn't it?
Re: M07-18   [#permalink] 21 Apr 2016, 19:51

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# M07-18

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