GMAT Prep / Number Properties

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Source: — Data Sufficiency |

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by cramya » Sun Dec 07, 2008 3:50 pm
Picking numbers is the way to go here

Stmt I

x/y= 1 (or this can be written as x=y)

x=1 y=1 1/1=1 yes x=1

x=2 y=2 2/2=1 x is not equal to 1

INSUFF

Stmt II

XY=1

x=2 y=1/2 xy=1 x is not equal to 1
x=1 y=1 xy=1 and x = 1

INSUFF

Combined

x=y
and xy=1

only possible when x=1 and y=1

C)

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by niraj_a » Mon Dec 08, 2008 10:30 am
@ cramya

question. in C i did the following -

xy = x/y
xy^2 = x
y^2 = 1
so y = 1 or -1

so i chose E. where did i go wrong?

EDIT - nvm, y>0

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by cramya » Mon Dec 08, 2008 10:56 am
so y = 1 or -1
Given : x and y are greater than 0

Hope this helps!

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by niraj_a » Mon Dec 08, 2008 12:35 pm
true, i hate silly mistakes...