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M07-18

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21 Apr 2016, 22:36
shishirkum wrote:
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?

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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29 Jun 2016, 10:30
my two cents...

Try to think this way -
Condition: four snakes in the box (V, V, C, C).

Scenario 1: I put my hands inside the box and pull out 1C and 1V, Stat 1 satisfied and so does condition in question stem.
Scenario 2: I put my hands inside the box and pull out 1V and 1V, Stat 1 satisfies and so does condition in question stem.
Scenario 3: I put my hands inside the box and pull out 1C and 1C, Is this scenario possible without violating Stat 1? NO. If we consider stat 1 as true, this scenario fails.

PS: Stat 1 means if we pull two snakes from the box, both can be V or atleast one SHOULD be V.
Similarly, we can have "n" number of snakes inside the box. But, if we consider stat 1, we are bound to have only one cobra.

Stat 2: Not relevant.

Ans: A
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09 Jul 2016, 08:58
I think this is a poor-quality question and I don't agree with the explanation. Hi there, so for (1) in my opinion let us assume it is 2 snakes only in the box. it could be 1 cobra and 1 viper or 2 vipers and 0 cobras. two potential solutions. Or do you say because of the first sentence *there is atl east one viper and at least one cobra in the box* this tells us the other one must for sure be a cobra?
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09 Jul 2016, 11:00
Probably shows something about my personality trait thanks!

Posted from my mobile device
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10 Jul 2016, 01:39
Hi Bunuel, I think the wording - from any two snakes at least one is viper is the trick. Had it been from any three at least one is viper then I think it wont be sufficient. Correct?
Thanks
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10 Jul 2016, 05:17
Hi rakaisraka,

exactly. Because the first statement clearly informs us that at least one is a cobra and one a viper, that means if there were 2 only and if one is a viper the other one must be a cobra. So for those type of questions, it is crucial to NOT ignore the initial statement.

Bunuel, correct?
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12 Jul 2016, 08:03
I think this is a high-quality question and I agree with explanation.
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20 Jul 2016, 22:32
I think this is a high-quality question and I agree with explanation.
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23 Jul 2016, 16:00
Hi!
st 1 says atleast... so there could me one... and more also..
how can we stick to just one question..
thanks
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03 Aug 2016, 08:52
dukenukem wrote:
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.

I agree with you!

http://lsatblog.blogspot.com.br/2011/02 ... -some.html

One thing that got me to this question is the meaning of at least which means some ranging from few, several or many up to "all".

So, if "at least" ranges from 1 to "all",

but "all" is unreachable for every two pairs - because the constraint from the question stem said c>=1,

then the remaining is "at most."

Now, stretch the logic and test it to a greater number of "snakes".

Is this a 800+ question?
>> !!!

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21 Sep 2016, 02:41
I think it is a very nice question. It is challenging but it teaches you to very carefully read the questions stems.
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29 Sep 2016, 15:25
Just to make it simple, statement 1) assumes that possibility of getting 2 cobras when choosing a pair = 0.

From the question stem, there must be at least one cobra in the box. Therefore, at minimum, there must be 1 cobra.

However, if there were more than 1 cobra, there is still a chance to pick 2 cobras no matter how many vipers there are.

Even if we have 1,000 vipers to 2 cobras, probability of picking a pair and ending up with 2 cobras is not 0, although it's quite close to it.

Since statement says that you are getting at least one viper, it means that there can only be one cobra.

For example, if you had 1,000 vipers and 2 cobras and you picked 1 cobra.

Now the probability of picking another cobra becomes 1/1001 (1001 = 1000 vipers + 2 cobras - 1 cobra which was just picked). It is still not 0 and you can still end up with 2 cobras in a pair.

Therefore, there can only be 1 cobra.
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19 Oct 2016, 06:47
I answered this one incorrectly but after reading the explanation it's all become so clear.

Just imagine a box full of snakes - you can see all of them crawling there. Try and take 2 cobras out of it - you won't be able to because it will violate Statement (1). You can only take 1 cobra out. There can't be 0 cobras either based on the same statement. Therefore, 1 cobra.

A very nice question IMHO.
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13 Nov 2016, 05:12
I think it is a very good question that makes you think, I got it wrong but after reading through the discussion, it was clear. Just as a deduction:
Would it mean that there are only two cobras if the first statement was:
From any three snakes, there is at least one viper .......
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28 Nov 2016, 22:25
I think this is a high-quality question and the explanation isn't clear enough, please elaborate. I get that since out of the two snakes picked atleast one is viper. That makes another pick a cobra for sure. But this does not tell me about the number of cobras that the pandora box has.

According to the solution I agree that 1 cobra is for sure, but there could be 2, 3, . . 9, 10, 11 . . 100, etc out which one cobra, definitly, finds a place in the pic.
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28 Nov 2016, 22:29
rajeshkpandey wrote:
I think this is a high-quality question and the explanation isn't clear enough, please elaborate. I get that since out of the two snakes picked atleast one is viper. That makes another pick a cobra for sure. But this does not tell me about the number of cobras that the pandora box has.

According to the solution I agree that 1 cobra is for sure, but there could be 2, 3, . . 9, 10, 11 . . 100, etc out which one cobra, definitly, finds a place in the pic.

How can there be more than 1 cobra if from ANY two snakes from Pandora's box at least one is a viper?

Please read the previous pages of the discussion.
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11 Jan 2017, 11:52
I think this is a high-quality question and I agree with explanation.
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10 Feb 2017, 23:14
This is a Brilliant question.
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14 Mar 2017, 10:51
I am still confused. The question states there is at least 1 cobra and 1 viper, and asks about the number of cobras.
(1) says From any two snakes from Pandora's box at least one is a viper.
This means at most, there is 1 cobra from any two snakes. But we are still missing the total number of snakes, and "At least 1" does not mean "it is 1". What am I missing?
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14 Mar 2017, 11:56
mitko20m wrote:
I am still confused. The question states there is at least 1 cobra and 1 viper, and asks about the number of cobras.
(1) says From any two snakes from Pandora's box at least one is a viper.
This means at most, there is 1 cobra from any two snakes. But we are still missing the total number of snakes, and "At least 1" does not mean "it is 1". What am I missing?

This is a hard logical question.

(1) From any two snakes from Pandora's box at least one is a viper. Since from ANY two snakes one is a viper then there cannot be 2 (or more) cobras and since there is at least one cobra then there must be exactly one cobra in the box. Sufficient.
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