m11 Q18 : GMAT Club Tests

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m11 Q18 [#permalink]

08 Jul 2010, 14:13

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Question Stats:

66% (01:23) correct

33% (00:00) wrong

based on 0 sessions

\sqrt{7+\sqrt{48}}-\sqrt{3}=?

A. 1
B. 1.7
C. 2
D. 2.4
E. 3

[Reveal] Spoiler: OA

Last edited by Bunuel on 06 Jul 2012, 01:35, edited 1 time in total.

Edited the question and the OA.

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Re: m11 Q18 [#permalink]

08 Jul 2010, 15:36

honkergirl wrote:

\sqrt{7}+\sqrt{48}-\sqrt{3}

Choices:
a. 1.0
b. 1.7
c. 2.0
d. 2.4
e. 3.0

The explanation for this qtn tells us to simplify
\sqrt{7}+\sqrt{48}=4+4\sqrt{3}+3
This leads to answer choice 2.

Butif I use normal algebra somehow I get a different answer:
\sqrt{7} = 2.646
\sqrt{48}=4\sqrt{3}
\sqrt{3}=1.73

Answer:7.84

Can someone please point out where I'm going wrong?

Thanks,

HG

Yes you need to take the square root of the square root of 48. You have the problem written incorrectly.

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Re: m11 Q18 [#permalink]

08 Jul 2010, 17:51

Ahh... that explains...

Thanks lagomez =p

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Re: m11 Q18 [#permalink]

05 Jul 2012, 21:44

How can I use estimation to solve this? I tried using estimation ...but always get trapped in some wrong choice....what to do avoid getting a wrong answer when using estimation in a question that has answer choices that are too close?

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Re: m11 Q18 [#permalink]

06 Jul 2012, 01:34

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teal wrote:

The question should read.

\sqrt{7+\sqrt{48}}-\sqrt{3}=?

A. 1
B. 1.7
C. 2
D. 2.4
E. 3

\sqrt{7+\sqrt{48}}=\sqrt{7+4\sqrt{3}}=\sqrt{4+4\sqrt{3}+3}=\sqrt{(2+\sqrt{3})^2}=2+\sqrt{3}.

So, \sqrt{7+\sqrt{48}}-\sqrt{3}=2+\sqrt{3}-\sqrt{3}=2.

Answer: C.

P.S. It's not a good idea to use approximation for this question.
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Re: m11 Q18 [#permalink] 06 Jul 2012, 01:34

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m11 Q18

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