p,q,r,s consecutive no.

[j_shreyans]

If p, q, r, and s are consecutive integers, with p<q<r<s, is pr<qs?

(1) pq<rs

(2) ps<qr

Guys ,

Cant we do this question be letting p=1&-1 , q=2&-2 , r=3&-3 , s=4&-4 ?

Pls suggest me..

[[email protected]]

Hi j_shreyans,

This DS question requires that P<Q<R<S AND that the variables be consecutive integers. There are lots of groups of numbers to choose from. We could use:
All positives
P=1
Q=2
R=3
S=4

All negatives
P=-4
Q=-3
R=-2
S=-1

A "mix"
P=-2
Q=-1
R=0
S=1

To address your original question, if P = -1, then the negative values that you chose for the other variables are INCORRECT. P has to be the smallest number (so Q, R and S have to be GREATER than -1)

With that note, you should re-try this question. If you're still unsure of what to do, then post back here and I'll walk you through it.

GMAT assassins aren't born, they're made,
Rich

[pfg2181]

Rich,

Using your numbers for example:
Statement 1: pq<rs
(1)(2)<(3)(4)--> 2<12 TRUE
(-4)(-3)<(-2)(-1)--> 12<2 FALSE
(-2)(-1)<(0)(1)--> 2<0 FALSE

Statement 1 alone is sufficient.

Statement 2: ps<qr
(1)(4)<(2)(3)--> 4<6 TRUE
(-4)(-1)<(-3)(-2)--> 4<6 TRUE
(-2)(1)<(-1)(0)--> -2<0 TRUE

Statement 2 alone is not sufficient.

Knowing that your integers must be all positives and consecutive, one can reason that pr<qs

ANSWER:
(A)Statement 1 alone is sufficient, but statement 2 alone is not sufficient to answer the question[/u]

[[email protected]]

Hi pfg2181,

The examples that I offered to j_shreyans were meant to point out a small mistake in her thinking (and to encourage a thorough set of TESTs); they are not a complete set in-and-of themselvesl On certain questions, you would have to do MORE work to be sure that you had gotten the correct answer. That having been said, your answer is correct, but I do want to point out one small mistake in your thinking:

In Fact 1, the 4 values do NOT need to all be positive. You could use the following set of values:

P=-1
Q=0
R=1
S=2

These values "fit" all of the given information (including the info in Fact 1) and would also lead to a YES answer.

GMAT assassins aren't born, they're made,
Rich

[j_shreyans]

Hi Rich ,

I have tested the question will all possible values but didn't come to any conclusion.

for e.g. p=-1 , q=0 , r=1 , s=2

TARGET = pr<qs

statement 1 - pq<rs
(-1)(0)<(1)(2)
0<2 which is true
Now put this value in our target

pr<qs
(-1)(1)<(0)(2)
-1<0 satisfy

Statement 2 - ps<qr
(-1)(2)<(0)(1)
-2<0 - true

Now Target pr<qs

(-1)(1)<(0)(2)
-1<0 also sufficient.

I know i am wrong pls correct me .

I have put lots of time in this question but......uuufffff

OA is A

[j_shreyans]

Hi ,

Can you guys pls correct me and let me know where i am wrong?

[Matt@VeritasPrep]

Why not approach it this way:

p = p
q = p + 1
r = p + 2
s = p + 3

We want to know if p * (p + 2) < (p + 1) * (p + 3), which reduces to p² + 2p < p² + 4p + 3, or 0 < 2p + 3, or -3/2 < p. So the real question is "Is p > -3/2?"

S1 gives us p * (p + 1) < (p + 2) * (p + 3), which reduces to p² + p < p² + 5p + 6, or 0 < 4p + 6, or 0 < 2p + 3, or -3/2 < p. Success! SUFFICIENT

S2 gives us p * (p + 3) < (p + 1) * (p + 2), which reduces to p² + 3p < p² + 3p + 2, or 0 < 2. Not very helpful, obviously!