600 level question

This topic has expert replies
Source: — Data Sufficiency |

Master | Next Rank: 500 Posts
Posts: 135
Joined: Tue Oct 13, 2009 10:27 am
Thanked: 3 times

by boazkhan » Sat May 29, 2010 9:46 pm
IMO A ...OA?

Legendary Member
Posts: 759
Joined: Mon Apr 26, 2010 10:15 am
Thanked: 85 times
Followed by:3 members

by clock60 » Sun May 30, 2010 1:32 am
also got A
is x-y>0
(1)x=y-1
y-1-y=-1<0
suffiicent
(2)x/3+5=y
x-x/3-5=(2x-15)/3
the sign depends on the value of x
so insuffiicent

User avatar
Legendary Member
Posts: 1460
Joined: Tue Dec 29, 2009 1:28 am
Thanked: 135 times
Followed by:7 members

by selango » Sun May 30, 2010 2:12 am
From statement 1 , x=y-1 or y=x+1 -->y is always greater than x,Sufficient.

From statment 2,

x/3=y-5

x=3y-15

If y=7,x=6,x<Y

y=8,x=9,x>y

y=-1,x=-18,x<y

Insufficient.

Hence answer is A

Senior | Next Rank: 100 Posts
Posts: 36
Joined: Mon Apr 12, 2010 4:59 am

by amitu » Mon May 31, 2010 2:13 am
IMO C

a) if y is +ve then x=y -1 => x > y

if y is -ve then x = y -1 => x < y ( y = -3 , x = -4 )

b) not suff

but combining we can solve the equation

key in a is sign of y .

User avatar
Legendary Member
Posts: 1460
Joined: Tue Dec 29, 2009 1:28 am
Thanked: 135 times
Followed by:7 members

by selango » Mon May 31, 2010 2:19 am
amitu wrote:IMO C

a) if y is +ve then x=y -1 => x > y

if y is -ve then x = y -1 => x < y ( y = -3 , x = -4 )

b) not suff

but combining we can solve the equation

key in a is sign of y .
If y is +ve,from x=y-1,y>x.

if y=4,x=3

User avatar
Master | Next Rank: 500 Posts
Posts: 233
Joined: Mon Jun 09, 2008 1:30 am
Thanked: 5 times

by blaster » Mon May 31, 2010 10:15 pm
i don't know how statement 1) can be sufficient. the question not stated that x and y positive.

Master | Next Rank: 500 Posts
Posts: 161
Joined: Mon Apr 05, 2010 9:06 am
Location: Mumbai
Thanked: 37 times

by 4GMAT_Mumbai » Mon May 31, 2010 10:25 pm
i don't know how statement 1) can be sufficient. the question not stated that x and y positive.

The positivity or negativity of x or y does not matter.

Thinking in terms of the number line helps. (x = y-1) implies that wherever y is; x is one unit to its left. There is no dependence on the positivity or the negativity of x or y. Hence, x is always less than y.

Hope this helps. Thanks.