p: If t is in the set, t+2 is in the set.
q: If t+2 is in the set, t is in the set.

p does not imply q. You get 1 and 5 from p, but -3 from q. For all you know, -1 is the smallest number in the set : )

MM_Ed wrote:p: If t is in the set, t+2 is in the set.
q: If t+2 is in the set, t is in the set.

p does not imply q. You get 1 and 5 from p, but -3 from q. For all you know, -1 is the smallest number in the set : )

And for all we know, -1 is just another number in the set. It is easy to find that 1 is in the set, but one needs to consider that the set is infinite in both directions on the number line, which is why we don't stop at 1. I rarely rant when I get the wrong answer, but this question is poorly written.

edvhou812 wrote:

MM_Ed wrote:p: If t is in the set, t+2 is in the set.
q: If t+2 is in the set, t is in the set.

p does not imply q. You get 1 and 5 from p, but -3 from q. For all you know, -1 is the smallest number in the set : )

And for all we know, -1 is just another number in the set. It is easy to find that 1 is in the set, but one needs to consider that the set is infinite in both directions on the number line, which is why we don't stop at 1. I rarely rant when I get the wrong answer, but this question is poorly written.

Well people its an authentic question. source - Quantitave review, 2nd edition, no. 158
Can we have some expert comment please!!

Sorry, posted wrong answer.
The answer is D.
-1 is in the set, so the possibility of -3 cannot be determined.as -1 can be the first number.
So we add 2 to -1 = -1+2= 1,
we add 2 to 1 = 1+2= 3, and
we add another 2 to 3 = 3+2 = 5.
so the answer is, 1 and 5, both are possible!

MM_Ed wrote:p: If t is in the set, t+2 is in the set.
q: If t+2 is in the set, t is in the set.

p does not imply q. You get 1 and 5 from p, but -3 from q. For all you know, -1 is the smallest number in the set : )

hi, i know we shouldn't assume anything in GMAT, but here's a doubt:

first of all its not mentioned its a finite set or that -1 is the first element of the said set.

Sorry people, could anyone please clarify. this problem is really bugging me.

In absence of any information you cant follow your own inferences.
The question in no way instructs you to calculate all the possibilities around -1. I do understand that if -1 is not the first element of the set then it would be a result of -3. But in the absence of information to the contrary assume it to be the first term(I am using the word assume).

If the question had provided you the information that -1 is an element from somewhere in the middle of the set then your argument would have been valid.