Night reader wrote:Is q positive?

(1) qp^2 is not negative
(2) q^2 is positive

(2) q^2 is positive

q can be both negative and positive.

Not Sufficient.

(1) qp^2 is not negative

When p = 0 then q can be both -ve or +ve.

Not Sufficient.

Combine both: No Use as when p^2 = 0 then p = 0 and we cannot say anything about q.

IMO E

I fell for C, but shovan's explanation makes it clear that it should be E ?

bblast wrote:I fell for C, but shovan's explanation makes it clear that it should be E ?

First look, I was for A. But the question is testing the fundamentals:

When x is non-negative integer that means x can be Zero OR all positive integers.
When x is positive then x cannot be Zero.

I believe the answer is C.

The wording in the statements is very subtle:

(1) qp^2 is not negative. This means the value could be zero or positive. Whenever you square either a positive or a negative number squared the result is positive number. But we also need to check for zero, and zero squared is zero. So p^2 could be + or 0. And the same goes for q. In order to get a positive number, if p^2 is positive, then q must also be positive. But because we can't rule out a value of qp^2 = 0, q could = 0 or +.

INSUFFICIENT

(2) q^2 is positive. Following the logic of exponents above, a negative or a positive squared creates a positive, so q could either be negative or positive.

INSUFFICIENT

Together, we know qp^2 is not negative and we know that q^2 is positive. Through statement 2 we know that q is not zero, and therefore q must be a positive number in order to make statement 1 true.

Thus, the answer is C.

aleph777 wrote:I believe the answer is C.

The wording in the statements is very subtle:

(1) qp^2 is not negative. This means the value could be zero or positive. Whenever you square either a positive or a negative number squared the result is positive number. But we also need to check for zero, and zero squared is zero. So p^2 could be + or 0. And the same goes for q. In order to get a positive number, if p^2 is positive, then q must also be positive. But because we can't rule out a value of qp^2 = 0, q could = 0 or +.

INSUFFICIENT

(2) q^2 is positive. Following the logic of exponents above, a negative or a positive squared creates a positive, so q could either be negative or positive.

INSUFFICIENT

Together, we know qp^2 is not negative and we know that q^2 is positive. Through statement 2 we know that q is not zero, and therefore q must be a positive number in order to make statement 1 true.

Thus, the answer is C.

this is what I worked out before reading shovan's answer.

M confused now.

Whats the oa nightreader ?

hi aleph777
i think you miss that p^2 can be equals to 0, as we have no restrictions on p, if p^2=0, then
(-q)*0>=0 here q-ve
(q)*0>=0 here q+ve

clock60 wrote:hi aleph777
i think you miss that p^2 can be equals to 0, as we have no restrictions on p, if p^2=0, then
(-q)*0>=0 here q-ve
(q)*0>=0 here q+ve

Great point, Clock60!

I would have to go with E as well here.

OA is E

(1)
q*p^2 = not-negative = 0 or +ve
==> if (q*p^2 = positive) then - q = +ve
==> if (q*p^2 = 0) then q = 0 or p^2 = 0
==> if p^2 = 0 then q = +ve or -ve or 0
INSUFF

(2)
q^2 = +ve
==> q = +ve or -ve (not zero)
INSUFF

(1&2):
q = +ve or -ve

Hence - (E)

Night reader wrote:Is q positive?

(1) qp^2 is not negative
(2) q^2 is positive

If (1) was re-worded to say: q(p^2) is not positive than the OA would be A correct? I initially thought it was q(p^2) and not (qp)^2

Anurag@Gurome wrote:

thp510 wrote:

Night reader wrote:Is q positive?

(1) qp^2 is not negative
(2) q^2 is positive

If (1) was re-worded to say: q(p^2) is not positive than the OA would be A correct? I initially thought it was q(p^2) and not (qp)^2

So the question will be :
Is q positive?
(1) q(p^2) is not positive
(2) q^2 is positive


Solution:
Let us first consider (1) alone.
This means q(p^2) <= 0
Let q = 3 and p = 0.
Here, q(p^2) = 0 and q is positive.
Next, let q = -3 and p = 0.
Again, q(p^2) = 0 and q is negative.
So, we cannot say from (1) that q is always positive or not.
Hence, (1) alone is not sufficient to answer the question.
Next consider (2) alone.
It only means that q is not zero.
But we cannot say whether q is positive or not.
Or (2) alone is not sufficient.
Next, combine both the statements together and check.
Even on combining, we get that q can be positive or negative.
This can be verified using (p,q) as (0,-3) and (0, 3) respectively.
Or both statements together are not sufficient to answer the question.

The correct answer is (E).

Thanks Anurag. Yes, I forgot about 0 (which is like a "third" sign).

I have chosen C too ) and actually could not understand ur reasoning of rejecting C option. ((

we are not asked whether qp is positive. we are asked whether Q is positive.

stmt 1 qp^2 is not negative- insuff, since "not negative" means (+) or 0.

stmt 2 q^2 is positive -insuff, since q can be (+) or (-)

both stmts- because of stmt 1, q cant be (-), so q must be (+) . and yes p could still be 0, but it doesnt change the situation of q alone. q can not be 0, since from stmt 2 we know that q is either positive, or negative. 0 is neither positive, nor negative.

please explain me what is wrong in my way of thinking.

thnx