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Two men, A and B, are assigned to complete a piece of work. A and B st

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Math Expert
Joined: 02 Sep 2009
Posts: 50007
Two men, A and B, are assigned to complete a piece of work. A and B st  [#permalink]

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05 Jul 2017, 00:44
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Difficulty:

25% (medium)

Question Stats:

74% (01:32) correct 26% (01:46) wrong based on 171 sessions

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Two men, A and B, are assigned to complete a piece of work. A and B started working together and both worked till the end. How long would A, working alone, take to complete the work?

(1) 11 hours after A and B had started working, 45 percent of the work was still remaining.
(2) After the work was completed, it was found that A had done 60 percent of the work.

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Re: Two men, A and B, are assigned to complete a piece of work. A and B st  [#permalink]

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05 Jul 2017, 01:21
1. 11 hours after A and B had started working, 45 percent of the work was still remaining.
Knowing the combined rate of work alone, we cannot clearly tell how much of the work they do separately.
Hence it is not possible to find out how long would it take A to do the work on his own.
The only information it would take for them 220/9 hours to complete the work.(Insufficient)

2. After the work was completed, it was found that A had done 60 percent of the work.
If A had done 60% of work, B would have done the other 40% of the work.
However, not knowing the time they would take to complete the work,
we will not be able to tell how much time A would take to complete the work (Insufficient)

On combining the information presented in both the statements,
we have the time taken for both of them to complete the work and the percentage of work A does.
So we can find out how much work A does in an hour, with which we can how much time he takes to complete the entire work(Sufficient)
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Joined: 18 Aug 2016
Posts: 625
Concentration: Strategy, Technology
GMAT 1: 630 Q47 V29
GMAT 2: 740 Q51 V38
Re: Two men, A and B, are assigned to complete a piece of work. A and B st  [#permalink]

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05 Jul 2017, 01:43
Bunuel wrote:
Two men, A and B, are assigned to complete a piece of work. A and B started working together and both worked till the end. How long would A, working alone, take to complete
the work?

(1) 11 hours after A and B had started working, 45 percent of the work was still remaining.
(2) After the work was completed, it was found that A had done 60 percent of the work.

(1) Assume total work is 180 units After 11 hours (A does 1/a units in 1 hr and B does 1b units in 1 hr)

11/a + 11/b = 99 (55% of 180)

1/a + 1/b = 9 (in 1 hour they together finish 9 units of work)
But we dont know anything about a or b hence not sufficient

(2) says 1/a is 60% of the work done in 1 hr and 1/b is 40% if the work done in 1 hr
We dont know about a or b hence not sufficient

However on combining we can solve for 1/a and hence can get the answer
C Sufficient
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Joined: 11 Feb 2017
Posts: 192
Re: Two men, A and B, are assigned to complete a piece of work. A and B st  [#permalink]

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22 Jul 2017, 02:38
mynamegoeson wrote:
Bunuel wrote:
Two men, A and B, are assigned to complete a piece of work. A and B started working together and both worked till the end. How long would A, working alone, take to complete
the work?

(1) 11 hours after A and B had started working, 45 percent of the work was still remaining.
(2) After the work was completed, it was found that A had done 60 percent of the work.

(1) Assume total work is 180 units After 11 hours (A does 1/a units in 1 hr and B does 1b units in 1 hr)

11/a + 11/b = 99 (55% of 180)

1/a + 1/b = 9 (in 1 hour they together finish 9 units of work)

However on combining we can solve for 1/a and hence can get the answer
C Sufficient

How to solve by combining?
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Joined: 18 Nov 2009
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Location: Switzerland
Concentration: Entrepreneurship, Technology
GMAT 1: 740 Q47 V45
Re: Two men, A and B, are assigned to complete a piece of work. A and B st  [#permalink]

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07 Nov 2017, 06:07
Bunuel wrote:
Two men, A and B, are assigned to complete a piece of work. A and B started working together and both worked till the end. How long would A, working alone, take to complete
the work?

(1) 11 hours after A and B had started working, 45 percent of the work was still remaining.
(2) After the work was completed, it was found that A had done 60 percent of the work.

Would not the question precise that they are working each at his constant rates?
Re: Two men, A and B, are assigned to complete a piece of work. A and B st &nbs [#permalink] 07 Nov 2017, 06:07
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