Thank you for using the timer - this advanced tool can estimate your performance and suggest more practice questions. We have subscribed you to Daily Prep Questions via email.

Customized for You

we will pick new questions that match your level based on your Timer History

Track Your Progress

every week, we’ll send you an estimated GMAT score based on your performance

Practice Pays

we will pick new questions that match your level based on your Timer History

Not interested in getting valuable practice questions and articles delivered to your email? No problem, unsubscribe here.

Thank you for using the timer!
We noticed you are actually not timing your practice. Click the START button first next time you use the timer.
There are many benefits to timing your practice, including:

Re: MGMAT DS Problem [#permalink]
03 May 2008, 15:07

Answer is C

Explanation : p<q and p<r and we need to find if pqr<p

Statement 1 : pq<0 means both have opposite signs and therefore p must be -ve and q must be +ve as p<q as given pqr depends on sign of r. If r is +ve pqr<p If r is -ve pqr>p NOT SUFFICIENT

Statement 2 : pr<0 . As above both must have opposite signs and p must be negative and r must be +ve as p<r given again we cannot determine pqr<p as if r is +ve its true if r is -ve its not. NOT SUFFICIENT

Both together

pq<0 and pr<0 , therefore p is _ve q and r +ve which means pqr is negative but product will be less than p

Re: MGMAT DS Problem [#permalink]
04 May 2008, 06:37

GMAT TIGER wrote:

jbpayne wrote:

If p < q and p < r, is (p)(q)(r) < p?

(1) pq < 0

(2) pr < 0

Does anyone have a quicker method to determine positives and negatives? I can get this one right, but it just takes me too long.

E. if q=r=1,any -ve value for p makes p = pqr.

The poster a few posts above you proved that C is sufficient to prove that p is NOT greater than pqr.

This always confuses me too, but a DS-type question doesn't ask if the statement p > pqr is true; it asks if we can figure out, in all cases, whether it is true or it is false.

1) p is -ve and q is +ve r can be -ve or +ve insuffcient -- multiple solutions possible 2)p is -ve and r is +ve q can be -ve or +ve insuffcient -- multiple solutions possible

combined

p -ve and q and r are postive.

insuffcient. qr <1 or >1 two solutions possible. pqr<p or pqr>p

E _________________

Your attitude determines your altitude Smiling wins more friends than frowning

The question tells us that p < q and p < r and then asks whether the product pqr is less than p. Statement (1) INSUFFICIENT: We learn from this statement that either p or q is negative, but since we know from the question that p < q, p must be negative. To determine whether pqr < p, let's test values for p, q, and r. Our test values must meet only 2 conditions: p must be negative and q must be positive. p q r pqr Is pqr < p? -2 5 10 -100 YES -2 5 -10 100 NO

Statement (2) INSUFFICIENT: We learn from this statement that either p or r is negative, but since we know from the question that p < r, p must be negative. To determine whether pqr < p, let's test values for p, q, and r. Our test values must meet only 2 conditions: p must be negative and r must be positive. p q r pqr Is pqr < p? -2 -10 5 100 NO -2 10 5 -100 YES If we look at both statements together, we know that p is negative and that both q and r are positive. To determine whether pqr < p, let's test values for p, q, and r. Our test values must meet 3 conditions: p must be negative, q must be positive, and r must be positive. p q r pqr Is pqr < p? -2 10 5 -100 YES -2 7 4 -56 YES At first glance, it may appear that we will always get a "YES" answer. But don't forget to test out fractional (decimal) values as well. The problem never specifies that p, q, and r must be integers. p q r pqr Is pqr < p? -2 .3 .4 -.24 NO Even with both statements, we cannot answer the question definitively. The correct answer is E.

Given: p<q and p<r. Question: is pqr<p? --> is p(qr-1)<0?

(1) pq < 0 --> p and q have opposite signs, as given that p<q then p<0 and q>0 --> as p<0 then the question becomes whether qr-1>0 (in p(qr-1) first multiple is negative - p<0, so in order the product to be negative second multiple must be positive - qr-1>0) --> is qr>1? We know that q>0 but all we know about r is that p<r. Not sufficient.

(2) pr < 0 --> the same here: p and r have opposite signs, as given that p<r then p<0 and r>0 --> as p<0 then the question becomes whether qr-1>0 --> is qr>1? We know that r>0 but all we know about q is that p<q. Not sufficient.

(1)+(2) we have that: p<0, q>0 and r>0. Again question becomes: is qr>1? Though both q and r are positive their product still can be more than 1 (for example q=1 and r=2) as well as less then 1 (for example q=1 and r=\frac{1}{3}) or even equal to 1. Not sufficient.