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Re: Question Regarding Answer Choices in DS [#permalink]
17 Nov 2011, 08:30

I'll go with C. because p*q = 1 common in both. Whats OA?

Cheers! _________________

----------------------------------------------------------------------------------------- What you do TODAY is important because you're exchanging a day of your life for it! -----------------------------------------------------------------------------------------

Re: Question Regarding Answer Choices in DS [#permalink]
17 Nov 2011, 22:26

1

This post received KUDOS

Expert's post

SonyGmat wrote:

I have a question that might be way easy.. maybe its because of the late hour... anyway... I will simplify it as much as possible.

Question: Is p*q=1?

statement 1: p=0 or p*q=1

statement 2: q=0 orp*q=1

What would your answer be? A,B,C,D,E?

Answer will be (E). Here is the reason:

Both statements together can hold for two different values of p*q. p*q = 0 is possible. Both statements hold if p = 0 and q = 0. One condition of each statement is satisfied. p*q = 1 is possible too. Again, one condition of each statement is satisfied.

Hence, we cannot answer the question: Is p*q = 1? It may or may not be. Therefore, answer is (E).

Now think, if we change the question a little, what's the answer?

Question: Is p/q=1?

statement 1: p=0 or p/q=1

statement 2: q=0 orp/q=1

p.s. - If you would like to get my input on a particular post, just pm me the link. I open very few posts a day so I may not get to see your post otherwise. _________________

Re: Question Regarding Answer Choices in DS [#permalink]
18 Nov 2011, 02:06

VeritasPrepKarishma wrote:

Question: Is p/q=1?

statement 1: p=0 or p/q=1

statement 2: q=0 orp/q=1

p.s. - If you would like to get my input on a particular post, just pm me the link. I open very few posts a day so I may not get to see your post otherwise.

Thanks so much for your input! I will do so from now on

Re: Question Regarding Answer Choices in DS [#permalink]
18 Nov 2011, 07:44

VeritasPrepKarishma wrote:

Question: Is p/q=1?

statement 1: p=0 or p/q=1

statement 2: q=0 orp/q=1

p.s. - If you would like to get my input on a particular post, just pm me the link. I open very few posts a day so I may not get to see your post otherwise.

I concur with your explanation Karishma. Thx. For the above new questions, [highlight]my answer is C[/highlight] because the common answer to both equations is p/q=1. (q=0 is undefined)

Cheers! _________________

----------------------------------------------------------------------------------------- What you do TODAY is important because you're exchanging a day of your life for it! -----------------------------------------------------------------------------------------

Re: Question Regarding Answer Choices in DS [#permalink]
18 Nov 2011, 10:21

VeritasPrepKarishma wrote:

Capricorn369 wrote:

I concur with your explanation Karishma. Thx. For the above new questions, [highlight]my answer is C[/highlight] because the common answer to both equations is p/q=1. (q=0 is undefined)

Cheers!

It is a YES/NO question. That means that if we find a YES or a NO answer the statement is SUFFICIENT. If we have a YES and a NO answer it will be translated to a MAYBE which would make a statement INSUFFICIENT.

Evaluating Statement 2, we have already a YES from p/q=1. The question now is whether q=0 will be translate as NO which would make the statement INSUFFICIENT.

We know as a fact that q=0 and try to see whether p divided by q could ever equal 1.

I guess in your view since it's undefined it can never equal 1 therefore it is NO. Having already a YES would make statement B INSUFFICIENT.

In my view, even it is not stated in the question stem that q can never be 0, which is something that should be stated in order to define a division, it is common sense that q can never be zero.

Which would make q=0 an answer that we should not consider and therefore make statement B SUFFICIENT.

Re: Question Regarding Answer Choices in DS [#permalink]
18 Nov 2011, 11:20

SonyGmat wrote:

VeritasPrepKarishma wrote:

Capricorn369 wrote:

I concur with your explanation Karishma. Thx. For the above new questions, [highlight]my answer is C[/highlight] because the common answer to both equations is p/q=1. (q=0 is undefined)

Cheers!

It is a YES/NO question. That means that if we find a YES or a NO answer the statement is SUFFICIENT. If we have a YES and a NO answer it will be translated to a MAYBE which would make a statement INSUFFICIENT.

Evaluating Statement 2, we have already a YES from p/q=1. The question now is whether q=0 will be translate as NO which would make the statement INSUFFICIENT.

We know as a fact that q=0 and try to see whether p divided by q could ever equal 1.

I guess in your view since it's undefined it can never equal 1 therefore it is NO. Having already a YES would make statement B INSUFFICIENT.

In my view, even it is not stated in the question stem that q can never be 0, which is something that should be stated in order to define a division, it is common sense that q can never be zero.

Which would make q=0 an answer that we should not consider and therefore make statement B SUFFICIENT.

Exactly, I don't believe I have EVER seen a question from an official GMAT source that is unambiguous on whether a number can be divided by 0. In nearly every case where a possibility "could" exist where a divisor becomes 0, GMAT always states that that variable is not equal to 0.

Re: Question Regarding Answer Choices in DS [#permalink]
19 Nov 2011, 23:45

1

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Expert's post

Yes, good thinking. The answer for the new question would be (B). There is no way q can be equal to 0 since it is the denominator in p/q. Hence according to statement 2, p/q must be 1. You have to be careful about all such little things. _________________