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Fence

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by sk8ternite » Thu Aug 27, 2009 12:52 pm
Yves can paint a certain fence in 1/2 the time it takes Marcel to paint the same fence. If they work together, each at his own constant rate, how many hours will it take them to paint the fence?

(1) Yves can paint the fence by himself in 3 hours.
(2) Working together, each at his own constant rate, they can paint the fence in 1/2 the time it would take Marcel, working alone, to paint the fence.
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Source: — Data Sufficiency |

by pradeepsarathy » Thu Aug 27, 2009 1:31 pm
IMO A -

Stmt 1:
Yvess can work complete the task in 3 hours => marcel can complete the task in 6 hours
Sufficient

Stmt 2:
Let Marcel complete the task in 'x' hrs => Yvess will complete the task in 'x/2' hrs
In 1 hr they will complete, 1/x + 2/x part of the task
=> 3/x part of task in 1 hr
=> x/3 hrs to complete the whole task - working together ---------> A

=> Marcel will complete the task in 2x/3 hrs(deduced from stmt 2 and A)
=> in 1 hr marcel will complete 3/2x part of the task

=> Yvess will complete the task in x/3 hrs(deduced from question stem and A)
= > in 1 hr he will complete 3/x part of the task

working together they will complete - 9/2x (2x/3 + x/3) part of the task in 1 hr
=>2x/9 hrs to complete the whole task.

Since we do not know the value of 'x', this stmt is insufficient
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by bharathh » Thu Aug 27, 2009 1:54 pm
Answer is A

I

You know the rates of both and can calculate total time using 1/T = 1/3 + 1/(2.3)

So I is sufficient

II

Although we know that the total time to paint the fence is equal to the time Yves would do it in.. we do not know have a value for the time Yves would take for this task in this statement. So insufficient.
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by sk8ternite » Thu Aug 27, 2009 6:46 pm
OA is A.
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Re: Fence

by vikram_k51 » Thu Aug 27, 2009 11:34 pm
sk8ternite wrote:Yves can paint a certain fence in 1/2 the time it takes Marcel to paint the same fence. If they work together, each at his own constant rate, how many hours will it take them to paint the fence?

(1) Yves can paint the fence by himself in 3 hours.
(2) Working together, each at his own constant rate, they can paint the fence in 1/2 the time it would take Marcel, working alone, to paint the fence.

Will be A for this one.
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by Nina1987 » Thu Feb 18, 2016 7:12 am
regarding statement2:
Say Marcel can finish the work in x hrs. Then Vyes can finish the same work in 2x hrs. So they together can finish the work in
(2x^2)/3x hrs
The statement says, this time is equal to 'half the time it would take Marcel alone'. Thus
(2x^2)/3x = 2x/2 --> 2/3 = 1
I know that this statement is not SUFF but how can I get 2/3 = 1? What'm I doing wrong here?
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by GMATGuruNY » Thu Feb 18, 2016 7:29 am
Nina1987 wrote:regarding statement2:
Say Marcel can finish the work in x hrs. Then Vyes can finish the same work in 2x hrs. So they together can finish the work in
(2x^2)/3x hrs
The statement says, this time is equal to 'half the time it would take Marcel alone'. Thus
(2x^2)/3x = 2x/2 --> 2/3 = 1
I know that this statement is not SUFF but how can I get 2/3 = 1? What'm I doing wrong here?
Prompt:
(time for Y alone) : (time for M alone) = 1:2.
Statement 2:
(time for Y and M together) : (time for M alone) = 1:2.

The prompt and statement 2 contradict each other, indicating that the problem is flawed.
Ignore this problem.
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by Nina1987 » Thu Feb 18, 2016 7:37 am
Thanks for your reply NYGuru! Thats what I guessed. Can you believe it- it is an official question? It appeared in my GMATFocus tests. What are these guys doing at gmac?!?!
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by GMATGuruNY » Thu Feb 18, 2016 8:32 am
Nina1987 wrote:Thanks for your reply NYGuru! Thats what I guessed. Can you believe it- it is an official question? It appeared in my GMATFocus tests. What are these guys doing at gmac?!?!
I suspect that Statement 2 is intended to read as follows:
Working together, each at his own constant rate, they can paint the fence in 1/3 the time it would take Marcel, working alone, to paint the fence.

Perhaps Statement 2 appeared as intended on the GMAT but was transcribed incorrectly into GMATFocus.
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Followed here and elsewhere by over 1900 test-takers.
I have worked with students based in the US, Australia, Taiwan, China, Tajikistan, Kuwait, Saudi Arabia -- a long list of countries.
My students have been admitted to HBS, CBS, Tuck, Yale, Stern, Fuqua -- a long list of top programs.

As a tutor, I don't simply teach you how I would approach problems.
I unlock the best way for YOU to solve problems.

For more information, please email me (Mitch Hunt) at [email protected].
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