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myfish: Senior | Next Rank: 100 Posts; Posts: 67; Joined: Mon May 03, 2010 12:03 pm; Thanked: 3 times

by myfish » Fri May 11, 2012 1:58 pm

Are x and y both positive?

(1) 2x-2y=1
(2) x/y > 1

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Source: Beat The GMAT — Data Sufficiency | Fri May 11, 2012 1:58 pm

mathbyvemuri: Master | Next Rank: 500 Posts; Posts: 142; Joined: Thu Apr 26, 2012 3:24 am; Location: India; Thanked: 28 times

by mathbyvemuri » Fri May 11, 2012 7:43 pm

statement(1):
x-y=1/2
Any combinations of (+,+),(+,-),(-,+),(-,-) are possible for x and y.
=> alone is not sufficient

statement(2):
x>y if y is positive else x<y
=> either both x and y are positive or both re negative
=> alone is not sufficient

statements taken together:
won't be sufficient as not resulting in a unique solution.
Answer "E"

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Mohitbhatia880: Newbie | Next Rank: 10 Posts; Posts: 9; Joined: Sat Mar 17, 2012 8:36 am

by Mohitbhatia880 » Sun May 13, 2012 7:18 am

I agree (1) or (2) are INSUFFICIENT. but consider both of them together

(1) 2x-2y = 1
(2) x/y >1

Rephrasing (1)

x-y = 1/2
x = y + 1/2

Now substituting value of x in (2)

(y+1/2)/y >1

Solving:

1+ 1/2y > 1

so, 1/2y > 0 it means y >0 since x = y+1/2 s0 X >0 as well.

Hope it helps

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GmatKiss: Legendary Member; Posts: 2789; Joined: Tue Jul 26, 2011 12:19 amFollowed by: 43 members; Location: Chennai, India; Thanked: 206 times; GMAT Score:640

by GmatKiss » Mon May 14, 2012 3:46 am

IMO: E

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mathbyvemuri: Master | Next Rank: 500 Posts; Posts: 142; Joined: Thu Apr 26, 2012 3:24 am; Location: India; Thanked: 28 times

by mathbyvemuri » Mon May 14, 2012 4:05 am

I agree with Mohitbhatia880's answer option "C". There is a flaw in my earlier explanation. We should not compare the ranges of statements (1) and (2), as I did in my earlier reply.If both the statements are considered, try to solve both the equations and get to a conclusion if possible. The ranges can't be compared but only the values from the two statements can be compared.

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GMATGuruNY: GMAT Instructor; Posts: 15539; Joined: Tue May 25, 2010 12:04 pmFollowed by: 1906 members; Location: New York, NY; Thanked: 13060 times; GMAT Score:790

by GMATGuruNY » Mon May 14, 2012 4:30 am

I posted an explanation here:

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