Beat The GMAT

maihuna · Fri Oct 30, 2009 10:54 am

If a + b > - c, is a > 2?

(1) a + b + c > 8
(2) - a + b + c < - 4

This is a yes/no question so you should plug in. For statement 1, if you plug in a = 3, b = 5, c = 4, then you get an answer of “yes,” but if a = 1, b = 6, c = 2, then you get an answer of “no,” so you should write down BCE. Now try plugging in for statement 2. Remember, when you’re plugging into a yes/no question that begins “If . . .”, you have to find numbers that satisfy both the statement and the “If” part of the question. So if a = 3 and b = 2, then c could be - 4 and you get an answer of “yes.” Go ahead and try to get an answer of no. If a = 2 and b = 2, then, according to the original “If” constraint, c has to be greater than - 4. But - 2 + 2 + - 3.9 = - 3.9, which is greater than - 4. No matter what number for a < 2 you try to plug in, it won’t satisfy both the statement and the constraint. Therefore, the answer has to be B.

Any better explanation possible, i thought of this one:
Given a+b+c>0 1 says the same thing, 2 says :
a>-b-c, using 2, -a < -b-c-4 or a>b+c+4
adding the two: 2a>4 or a>2

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alexchow · Sun Nov 01, 2009 6:41 am

Looks like b.

(i) means a+b-8>-c but composition of a+b is not known.

(ii) subtract the inequalities

a+b > -c
-
-a+b > -4 -c
=
a-(-a)+b-b > -c-(-4-c)

--> 2a >4 ---> a>2

Sufficient.

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satish.nagdev · Sun Nov 01, 2009 11:31 am

IMO C,
we need both statements to determine a's value.

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tarun.kirla · Mon Nov 02, 2009 10:08 am

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satish.nagdev · Mon Nov 02, 2009 8:33 pm

I approached in this way

given
1) a + b + c > 8 ==> no info about a
2) - a + b + c < - 4 ==> no info about a

together

(1) a + b + c > 8
(2) - a + b + c < - 4 ==> a -b -c >4
a + b + c + a - b - c > 8 + 4
2a > 12
a > 6

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mehravikas · Mon Nov 02, 2009 9:04 pm

IMO - C

Solution - same as above

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2010gmat · Tue Nov 03, 2009 2:50 am

maihuna...i agree with you..ans should be B

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crackgmat007 · Tue Nov 03, 2009 2:32 pm

1. Not sufficient - as it says a + b + c > 8

2. Sufficient - add inequalities given in question

a + b + c > 0

a - b - c > 4 ( multiply stmt 2 with with -1)

We get a > 2