700+ Quant DS.

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700+ Quant DS. [#permalink]

09 Feb 2010, 09:55

Hey Fellows,
Try this question.

Is a^2 + b^2 >= 130?

1. a/b = 3/11.
2. a < 3.

OA

[Reveal] Spoiler:

Last edited by punzoo on 09 Feb 2010, 10:43, edited 1 time in total.

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Re: 700+ Quant DS. [#permalink]

09 Feb 2010, 10:00

punzoo wrote:

Hey Fellows,
Try this question.

Is a^2 + b^2 >= 130?

1. a/b = 3/7.
2. a < 3.

OA

[Reveal] Spoiler:

E

1) It's a ratio, so a & b can be any number. Insuff
2) Not helpful; a = -infinity to +2. Insuff

combine, you get nothing.

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Re: 700+ Quant DS. [#permalink]

12 Feb 2010, 20:00

Ans:E

1. a/b = 3/11.
when a=6, b=22 then a^2 + b^2>130
when a=.6, b=2.2 then a^2 + b^2<130
So insufficient

2. a < 3.
when a=.6, b=2.2 then a^2 + b^2<130
when a=-6, b=-22 then a^2 + b^2>130
So insufficient

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Re: 700+ Quant DS. [#permalink]

13 Feb 2010, 00:16

punzoo wrote:

Hey Fellows,
Try this question.

Is a^2 + b^2 >= 130?

1. a/b = 3/11.
2. a < 3.

OA

[Reveal] Spoiler:

I m confused between C n E. pls letme know where I m wrong.

clearly 2nd eq is not sufficient.
Take 1st eq... take a=3x and b =11x

put in the question.....we get 9x^2 + 121x^2 >= 130

=> 130x^2 >=130
x^2>=1, thus we need to know whether this satisfy or not.
If we consider eq 2... a<3 that means x<1

Thus this should be C...but one case when x=1 we hav not consider this might take it to E.
Pls advice.
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Re: 700+ Quant DS. [#permalink]

13 Feb 2010, 06:29

gurpreetsingh wrote:

punzoo wrote:

Hey Fellows,
Try this question.

Is a^2 + b^2 >= 130?

1. a/b = 3/11.
2. a < 3.

OA

[Reveal] Spoiler:

You did everything right, except the last step: x^2\geq{1} --> x\leq{-1} or x\geq{1} --> a\leq{-3} or a\geq{3}. So still E.

You can use number plugging when considering statements together: For a=0.3 and b=1.1 answer is NO, but for a=-3 and b=-11 answer is YES.

Hope it helps.
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Re: 700+ Quant DS. [#permalink] 13 Feb 2010, 06:29

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