work problem

[nisha.menon294]

Machines X and Y work together at their respective rates. How many more hours does it take Machine Y working alone to fill an order of a certain size than it takes machine X , working alone ?

1) Machines X and Y working together fill a production order of this size in two thirds of the time machine X, WORKING alone does
2)Machine Y working alone fills a production order of this size in twice the time that machine X ,working alone does .

[liferocks]

IMO ans is E either of the statement will not provide the difference in hours
statement 1 we get when machine X completes 2/3 of the work machine Y completes 1/3 rd of the work
So machine Y takes twice the time that machine X ,working alone does.

statement 2 also provides the same relation as statement 1
both the statements provide the ratio of rate of work for machine X and Y but does not speak about the time takes in hours for either of them.

hence ans is E

[neoreaves]

IMO D

Lets say mahine x can finish an order in x hrs
machine y can finish an order in y hrs

what we need to know = x - y


1)
working together they will finish an order in xy/ (x+y) hrs

xy / (x+y) = 2x/3

solving this gave me
2x = y

thus x - y = x - 2x = -x

so sufficient

2) gives us 2x = y

thus sufficient

[harshavardhanc]

IMO D

Lets say mahine x can finish an order in x hrs
machine y can finish an order in y hrs

what we need to know = x - y


1)
working together they will finish an order in xy/ (x+y) hrs

xy / (x+y) = 2x/3

solving this gave me
2x = y

thus x - y = x - 2x = -x

so sufficient

2) gives us 2x = y

thus sufficient

X was a variable chosen for our convenience. They have not provided a value for it. Had we known what numbers X and Y stand for, we would have been able to say that D is the credited response.

[Stuart@KaplanGMAT]

Machines X and Y work together at their respective rates. How many more hours does it take Machine Y working alone to fill an order of a certain size than it takes machine X , working alone ?

1) Machines X and Y working together fill a production order of this size in two thirds of the time machine X, WORKING alone does
2)Machine Y working alone fills a production order of this size in twice the time that machine X ,working alone does .

Here's an important rule for ds:

if a question asks for a specific value, you need at least 1 number somewhere in the information to solve.

Here, the question asks "how many more hours", i.e. we want an actual number, not just a ratio.

There are no actual numbers in the stem or either statement, therefore the answer must be (E).

[neoreaves]

hmm yes you guys are right ...that was such a silly mistake .... but time pressure does get you at times and thats what did it for me here ....