DS-Plz. help

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gmat009: Master | Next Rank: 500 Posts; Posts: 458; Joined: Sun Aug 31, 2008 10:44 amFollowed by: 1 member; Thanked: 3 times

by gmat009 » Tue Oct 07, 2008 12:39 pm

Is xy > (x^2)(y^2)
(1) 14(x^2) = 3
(2) y^2 = 1

A. Statement (1) ALONE is sufficient, but statement (2) alone is not sufficient.
B. Statement (2) ALONE is sufficient, but statement (1) alone is not sufficient.
C. BOTH statements TOGETHER are sufficient, but NEITHER statement ALONE is sufficient.
D. EACH statement ALONE is sufficient.
E. Statements (1) and (2) TOGETHER are NOT sufficient.

OA is E , IMO C.

Can someone plz. explain

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Source: Beat The GMAT — Data Sufficiency | Tue Oct 07, 2008 12:39 pm

gmat2010: Junior | Next Rank: 30 Posts; Posts: 29; Joined: Mon Sep 01, 2008 3:24 pm; Thanked: 3 times

Re: DS-Plz. help

by gmat2010 » Tue Oct 07, 2008 1:02 pm

gmat009 wrote:Is xy > (x^2)(y^2)
(1) 14(x^2) = 3
(2) y^2 = 1

A. Statement (1) ALONE is sufficient, but statement (2) alone is not sufficient.
B. Statement (2) ALONE is sufficient, but statement (1) alone is not sufficient.
C. BOTH statements TOGETHER are sufficient, but NEITHER statement ALONE is sufficient.
D. EACH statement ALONE is sufficient.
E. Statements (1) and (2) TOGETHER are NOT sufficient.

OA is E , IMO C.

Can someone plz. explain

It's E because y can be either 1 or -1 from statement B. In that case, the answer will give you conflicting results.

It's a trick question, i first thought it was C as well...

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raju232007: Master | Next Rank: 500 Posts; Posts: 133; Joined: Sat Dec 29, 2007 2:43 am; Thanked: 12 times

by raju232007 » Fri Oct 10, 2008 8:12 am

statement 1

14*x^2=3
x=sqrt(3/14),-sqrt(3/14)
This statement doesn't tell anything about the value of y
Insufficient

statement 2

y^2=1
y=1,-1

This statement doesn't tell anything about the value of x
Insufficient

Combining both the statements we have

4 cases should be considered
1.when both are positive
2.when both are negative
3.when x is positive and y is negative
4.when x is negative and y is positive

case 1
sqrt(3/14)*1>3/14*1....yes
(P.s the square root of a proper fraction results in a number greater than the fraction itself)

case 3
sqrt(3/14)*-1>-3/14.....The ans is no

Hence the ans should be E

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