Data Sufficiency

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.

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

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.

OA is A.

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.

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?

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.

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?!?!

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.