GMAT:Punch of the Week(16-March-09)

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Sureshbala

GMAT:Punch of the Week(16-March-09)

Author: Sureshbala

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What is "Punch Of The Week"?

Every week Learnhub's team will post one question each on Verbal Ability and Quantitative Ability of the GMAT Test Preparation
Members can post their answers along with explanations for the next one week.
After one week, Learnhub's team will post the official answer along with the explanation.Besides answering the previous week's questions, Learnhub's Team will come up with the next set of questions for that week as well.

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	Please bear in mind that only Learnhub's Team members have the privilege of posting questions here. Questions posted by other members will not be entertained and hence will be deleted immediately.

"Punch Of The Week" Team Members

This Week's Punches

Sentence Correction

The jurors agreed that of all the reasons the defense attorney gave for finding his client not guilty, the last two of them were the most absurd.

(A) the last two of them were the most absurd.
(B) the latter two were the most absurd
(C) the last two of these were the most absurd
(D) the last two of them were the absurdest.
(E) the last two were the most absurd.

Problem Solving

$If \quad \frac{a}{b}+\frac{a+10b}{b+10a}=2,$ $a \neq b, \quad find \quad \frac{a}{b}$

(A)0.6
(B)0.7
(C)0.8
(D)0.9
(E)0.4

Posted on 23-March-09

So, folks here are the correct answers

Sentence Correction
The correct answer is (E). In (A), (C),and (D), "of them" or "of these" is superfluous. In (B), "the latter" is incorrect.Since there are more than two items to refer back to, the correct term is "the last." (If four items were specified, the writer could refer to "the latter two," as distinct from "the former two," but "of allthe reasons" implies many more than four.)

Problem Solving

The correct answer is C.
$Let\quad \frac{a}{b}=x$
$\frac{a}{b}+\frac{a+10b}{b+10a}=2$
$\Rightarrow x+\frac{bx+10b}{b+10bx}=2$
$\Rightarrow x + \frac{x+10}{1+10x}=2$
$\Rightarrow 10x^2-18x+8=0$
$\Rightarrow 5x^2-9x+4=0$
$\Rightarrow 5x^2-5x-4x+4=0$
$\Rightarrow 5x(x-1)-4x(x-1)=0$
$\Rightarrow (x-1)(5x-4)=0$
$\Rightarrow x = 1 or x = \frac{4}{5}$
$\Rightarrow \frac{a}{b}=1$ or $\frac{a}{b}=\frac{4}{5}$
Since it is given that $a \not= b,$ the value of $\frac{a}{b}=\frac{4}{5}=0.8$

Click here for the next week's Punch

Click here for last week's Punch and explanatory answers for the same

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14 Comments

rkmittal said – Mon, 16 Mar 2009 09:25:29 -0000 ( Flag Edit Link )

SC: E &

Problem solving: C (0.8)

Solving, we get a(b+10a)+b(a+10b)=2b(b+10a)

or ab+10a^{2+ab+ 10b}2=2b^2+20ab

or 10a2+8b^2-18ab=0

Dividing the equation by ab, we get:

10a/b+8b/a-18=0

Let a/b=k, we get:

10k+8/k-18=0, or

10k2-18K+8=0, or

5k^2-9k+4=0

Solving for k, i.e a/b, we get k = a/b = 0.8
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sanju09 said – Mon, 16 Mar 2009 10:02:52 -0000 ( Flag Edit Link )

Problem Solving

Let a/b = x, so that the given equation reduces to

x + [(x + 10)/(1 + 10 x)] = 2, or

x + 10 x ^ 2 + x + 10 = 2 + 20 x, or

10 x ^ 2 – 18 x + 8 = 0, or

(10 x – 8) (x – 1) = 0

now x – 1 cannot be zero since it is given that a is not b; hence 10 x – 8 = 0, or

x = 0.8, go with C.
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tyagideepa said – Mon, 16 Mar 2009 15:33:01 -0000 ( Flag Edit Link )

SC – E. Quant – C.
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vsatyaramesh said – Tue, 17 Mar 2009 02:30:46 -0000 ( Flag Edit Link )

The answer to SC is E. All the others have pronoun reference errors.

The answer to PS is C.
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i_m_wat_i_m said – Tue, 17 Mar 2009 05:38:32 -0000 ( Flag Edit Link )

for sentence correction E and for Ps its C 0.8
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dku12 said – Tue, 17 Mar 2009 07:02:35 -0000 ( Flag Edit Link )

SC-E, PS-C
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mahatma_rohit said – Tue, 17 Mar 2009 11:01:37 -0000 ( Flag Edit Link )

For SC, E is the best choice. For PS, C is the correct answer.
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prajay said – Wed, 18 Mar 2009 06:54:33 -0000 ( Flag Edit Link )

SC – E, PS -C
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dgr8onerip said – Wed, 18 Mar 2009 15:45:11 -0000 ( Flag Edit Link )

sc – e quant- c
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shaileshjain said – Thu, 19 Mar 2009 15:40:16 -0000 ( Flag Edit Link )

Interesting Quant question
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shaileshjain said – Thu, 19 Mar 2009 15:40:47 -0000 ( Flag Edit Link )

Interesting Quant question
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Stuti_kushwaha said – Thu, 19 Mar 2009 17:58:02 -0000 ( Flag Edit Link )

1-E 2-C
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prabir2001 said – Sun, 22 Mar 2009 22:18:06 -0000 ( Flag Edit Link )

SC 1- Ans : (E) the last two were the most absurd. This option is crisp and clear.

QA 2 – Ans : (C) 0.8 Just expand and solve.
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Sureshbala said – Tue, 24 Mar 2009 06:40:03 -0000 ( Flag Edit Link )

So, folks here are the correct answers

Sentence Correction
The correct answer is (E). In (A), (C),and (D), “of them” or “of these” is superfluous. In (B), “the latter” is incorrect.Since there are more than two items to refer back to, the correct term is “the last.” (If four items were specified, the writer could refer to “the latter two,” as distinct from “the former two,” but “of allthe reasons” implies many more than four.)