pqrs

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pqrs

by sanjib » Fri Jul 03, 2009 6:42 am
If p,q,r, and s are nonzero numbers, is
(p – 1)(q - 2)2(r – 3)3(s – 4)4 ≧ 0?
(1) q > 2 and s > 4
(2) p > 1 and r > 3

OA is B
Source: — Data Sufficiency |

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Re: pqrs

by ssmiles08 » Fri Jul 03, 2009 6:50 am
sanjib wrote:If p,q,r, and s are nonzero numbers, is
(p – 1)(q - 2)2(r – 3)3(s – 4)4 ≧ 0?
(1) q > 2 and s > 4
(2) p > 1 and r > 3

OA is B
I think you mean (p – 1)*(q - 2)^2*(r – 3)^3*(s – 4)^4 ≧ 0?

1) not sufficient. If r < 3, and P > 1, the product could be <= 0.

2) Sufficient. (q - 2)^2 and (s – 4)^4 will always yield positive results since they are even powers. we know that p > 1 and r > 3, which means (p – 1) and (r – 3) are positive. now all of them are positive. so the product is >= 0.

(B)