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# If (ab/cd)<0, is bc>ad? 1) cd>ab 2)b<c<0 A)1

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Intern
Joined: 05 Apr 2008
Posts: 23

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02 Sep 2008, 22:32
This topic is locked. If you want to discuss this question please re-post it in the respective forum.

1) cd>ab
2)b<c<0
A)1 alone is sufficient
B)2 alone is sufficient
C)1 and 2 together are sufficient to answer the Q
D)Either 1 or 2 are sufficient
E)Neither 1 or 2 are sufficient
Director
Joined: 14 Aug 2007
Posts: 727
Re: Math Question - Datta Sufficiency [#permalink]

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03 Sep 2008, 00:24
HVD1975 wrote:
1) cd>ab
2)b<c<0
A)1 alone is sufficient
B)2 alone is sufficient
C)1 and 2 together are sufficient to answer the Q
D)Either 1 or 2 are sufficient
E)Neither 1 or 2 are sufficient

B.

given that ab/cd is negative 1) tells us that c and d have same sign and a&b have different signs.

2) tells us that both b and c are -ve, thus bc has to be positive.

it also tells us that b/c is +ve, hence a or d must have -ve sign, which makes ad -ve.
SVP
Joined: 07 Nov 2007
Posts: 1799
Location: New York
Re: Math Question - Datta Sufficiency [#permalink]

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03 Sep 2008, 06:21
HVD1975 wrote:
1) cd>ab
2)b<c<0
A)1 alone is sufficient
B)2 alone is sufficient
C)1 and 2 together are sufficient to answer the Q
D)Either 1 or 2 are sufficient
E)Neither 1 or 2 are sufficient

(ab/cd)<0
means --> ab/cd is negative
1) cd>ab
then cd must be postive ( both c and d can be postive or negative)
ab must be -ve ( a -ve and b +ve or a +ve and b -ve)

when c +ve , d+ve a -ve b+ve
when c -ve , d-ve a -ve b+ve

Insuffcient
2)b<c<0
both b, c are negative --> bc +ve
(ab/cd)<0 --> a or d must be negative. --> so ad --> negative

suffcient

B
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Re: Math Question - Datta Sufficiency   [#permalink] 03 Sep 2008, 06:21
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