Question: Whether P = +P or -P.

From statement 1:

P is prime. Only positive integers are prime, then P = P.
Sufficient.

From statement 2:

P is even, Only positive integers are even, then P = P.
Sufficient.

D is the answer.

Question: Is p = |p|

Statement 1 : P is a prime.. All prime numbers are positive numbers..
Sufficient.

Statement 2 : P is even. But even numbers can be both positive or negative.
Not Sufficient.

Answer A

Yes we don't take care of these things and ultimately do mistake.. Good that this question came up so that we added new info in our preparation matrix.

gmatbusters
as per statement 1 , wont we get many values of P i.e 2,3,5,7 , i think it would be insufficient

The question is only asking if p is positive or not. So only Value you get is "Yes it is +ve".

Hi Archit3110



You are right that in DS , we need a definite answer.

But the answer should be definite for the question asked in the question stem.

Question: is Mod p = p

if Answer = yes , it is definite

if answer = No, it is definite

but if Answer = Yes in some cases and No in some cases, it is not definite.



As per Statement1: As all prime numbers are positive, hence Mod p = p, Answer = yes , it is definite.

As per Statement 2:

if p = 2, answer = yes

if p = -2, answer = No, Answer = Yes in some cases and No in some cases. Hence it is NOT DEFINITE.



Answer = A
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Hi Archit3110,
That's the beauty of GMAT DS questions.. You have to be very sure what question is asking.

Lets take an example..
If I ask you .. Do you want to visit a Hill station ?
The answer you will give is either Yes or No or Maybe.
So, Yes or No are definite answer and Maybe is not definite.

Here there can be many hillstation but that doesn't matter as question is asked if you want to visit or not.
Yes - Definite
No - Definite
Maybe - Indefinite.

If you started thinking kulu, manali, Shimla .. you are gone .

So, Try to analyse question first what the question is asking. The actual GMAT questions will be so simple that you can sometimes fall in the trick and mark wrong answers.

Hope that helps.

Here the question is "Is p = |p|?" which needs to be answered in the form of YES/NO

As soon as we use the first statement which states that p is Prime (which are essentially positive integers) then we can answer the question with a Definitely YES hence statement 1 alone is sufficient.

Since this alone is sufficient so we can strike off option C at this stage only so that the question of C to be a potential answer does NOT arise while using statement 2 alone.

I hope this helps!!1[/quote]

GMATinsight :

For elimination of options I do follow AD/BCE rule in DS..

Sir, I understood where I was going wrong in my assumption .. .. thanks for replying..

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