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M02-12

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Math Expert
Joined: 02 Sep 2009
Posts: 51035

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15 Sep 2014, 23:17
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Difficulty:

35% (medium)

Question Stats:

68% (01:08) correct 32% (01:08) wrong based on 190 sessions

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If the remainder is 2 when $$x$$ is divided by 5, then is $$x$$ divisible by 7?

(1) $$x$$ is a prime number

(2) $$x + 3$$ is a multiple of 10

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Joined: 02 Sep 2009
Posts: 51035

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15 Sep 2014, 23:17
Official Solution:

Statement (1) by itself is insufficient. If $$x$$ is a prime number, then $$x$$ can be 7, 17, 37, and so on. 7 is divisible by 7, but 17 and 37 are not.

Statement (2) by itself is insufficient. If $$x = 7$$, then the answer to the question is yes. If $$x = 17$$ then the answer is no; if $$x = 37$$ then the answer is no.

Statements (1) and (2) combined are insufficient. $$x$$ can still be 7, 17, 37, etc.

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Joined: 25 Dec 2012
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30 Mar 2015, 17:33
Bunuel wrote:
Official Solution:

Statement (1) by itself is insufficient. If $$x$$ is a prime number, then $$x$$ can be 7, 17, 37, and so on. 7 is divisible by 7, but 17 and 37 are not.

Statement (2) by itself is insufficient. If $$x = 7$$, then the answer to the question is yes. If $$x = 17$$ then the answer is no; if $$x = 37$$ then the answer is no.

Statements (1) and (2) combined are insufficient. $$x$$ can still be 7, 17, 37, etc.

Hi Brunel, I got the same answer, but it took me more than 3 minutes to confirme my answer. Do you know if is it possible to do the question in a faster way?

Regards,
Gonzalo
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Joined: 18 Apr 2015
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13 Nov 2015, 10:14
Bunuel wrote:
Official Solution:

Statement (1) by itself is insufficient. If $$x$$ is a prime number, then $$x$$ can be 7, 17, 37, and so on. 7 is divisible by 7, but 17 and 37 are not.

Statement (2) by itself is insufficient. If $$x = 7$$, then the answer to the question is yes. If $$x = 17$$ then the answer is no; if $$x = 37$$ then the answer is no.

Statements (1) and (2) combined are insufficient. $$x$$ can still be 7, 17, 37, etc.

Hi Bunuel,

Statement (1) Says X is prime. How is one of the answers then 7? 1 is not a prime number please help me understand then how 5(1) +2 is in this range then? I'm likely misunderstanding your given solution.

Thanks
Math Expert
Joined: 02 Sep 2009
Posts: 51035

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14 Nov 2015, 09:39
stov10 wrote:
Bunuel wrote:
Official Solution:

Statement (1) by itself is insufficient. If $$x$$ is a prime number, then $$x$$ can be 7, 17, 37, and so on. 7 is divisible by 7, but 17 and 37 are not.

Statement (2) by itself is insufficient. If $$x = 7$$, then the answer to the question is yes. If $$x = 17$$ then the answer is no; if $$x = 37$$ then the answer is no.

Statements (1) and (2) combined are insufficient. $$x$$ can still be 7, 17, 37, etc.

Hi Bunuel,

Statement (1) Says X is prime. How is one of the answers then 7? 1 is not a prime number please help me understand then how 5(1) +2 is in this range then? I'm likely misunderstanding your given solution.

Thanks

The stem says that the remainder is 2 when x is divided by 5.
(1) says that x is a prime number.

x can be 7 because 7 is a prime and 7 divided by 5 gives the remainder of 2.
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10 Apr 2017, 09:12
Hi Bunuel

From the question we can make out that x has ones digit of 2 or 7.

1. This eliminates all the nos. with 2 as units digit.
So, as you said the no. could be 7, 17, 37, 57 etc. But none of these, or any of the greater prime nos. with units digit as 7, are divisible by 7.
Hence, sufficient.

2. Statement one is a subset of statement 2, without the "prime no. condition", therefore can also have a no. like 77.
Hence, not sufficient.

Ans: Option 1

Math Expert
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Posts: 51035

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10 Apr 2017, 09:49
bibinphilips wrote:
Hi Bunuel

From the question we can make out that x has ones digit of 2 or 7.

1. This eliminates all the nos. with 2 as units digit.
So, as you said the no. could be 7, 17, 37, 57 etc. But none of these, or any of the greater prime nos. with units digit as 7, are divisible by 7.
Hence, sufficient.

2. Statement one is a subset of statement 2, without the "prime no. condition", therefore can also have a no. like 77.
Hence, not sufficient.

Ans: Option 1

I don't understand what you mean by the red part.

For (1): x can be 7 so divisible by 7 or say 17, so not divisible by 7. Two different answers not sufficient.
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01 Sep 2018, 19:09
Bunuel wrote:
If the remainder is 2 when $$x$$ is divided by 5, then is $$x$$ divisible by 7?

(1) $$x$$ is a prime number

(2) $$x + 3$$ is a multiple of 10

Hey Bunuel

Just to understand, x can be 2 also in general and even for answer choice 1. 2 divided by 5 will leave the remainder as 2. Am I missing something?

Thanks
Math Expert
Joined: 02 Sep 2009
Posts: 51035

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02 Sep 2018, 01:53
gmatlife wrote:
Bunuel wrote:
If the remainder is 2 when $$x$$ is divided by 5, then is $$x$$ divisible by 7?

(1) $$x$$ is a prime number

(2) $$x + 3$$ is a multiple of 10

Hey Bunuel

Just to understand, x can be 2 also in general and even for answer choice 1. 2 divided by 5 will leave the remainder as 2. Am I missing something?

Thanks

Yes, x can be 2, for (1) because 2 divided by 7 gives the remainder of 2.
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Re: M02-12 &nbs [#permalink] 02 Sep 2018, 01:53
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