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# Machines X and Y produce identical bottles at different

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Intern
Joined: 10 Oct 2011
Posts: 35
Concentration: Operations, Marketing
GPA: 3.1
WE: Project Management (Non-Profit and Government)
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Machines X and Y produce identical bottles at different [#permalink]  08 Nov 2011, 19:21
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Difficulty:

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Question Stats:

67% (01:51) correct 33% (01:09) wrong based on 33 sessions
Machines X and Y produce identical bottles at different constant rates. Machine X, operating alone for 4 hours, filled part of the production lot; then Machine Y, operating along for 3 hours, filled the REST of this lot.

How many hours would it have taken Machine X operating alone to fill the entire production lot?

1) Machine X produced 30 bottles per minute.
2) Machine X produced twice as many bottles in 4 hours as Machine Y produced in 3 hours.

My work:

Bottles = (rateX)4 + (rateY)3 *Did not forget to convert minutes to hours

1) RateX = 30 b/min = 1800 b/hr
Xbottles = 1800(4) = 7200 bottles

Insuff

2) Bottles Y = 1/2 Bottles X

I went with putting them together, getting the total number of bottles produced and backing out the rate for the answer. WRONG.

I have the answer, I just don't understand it.
[Reveal] Spoiler: OA

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Kudos [?]: 61 [0], given: 46

Re: DS Work Problem [#permalink]  08 Nov 2011, 20:39
I recommend you to approach the question as mentioned below -

As question is asking to find time taken by Machine X operating alone to fill the entire production lot and we've know that production lot (a) partily filled by X in 4 hrs (b) Rest filled by Y in 3 hrs.
As we dont have any information about Part(b), we need to find or establish a relationship between X and Y so that we can calculate the whole period in terms of X. Fortunately, The relation is clearly given in (2) Machine X produced twice as many bottles in 4 hours as Machine Y produced in 3 hours.

Hence, B is the answer. No calculation required.

Hope it helps!
Cheers!
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Intern
Joined: 10 Oct 2011
Posts: 35
Concentration: Operations, Marketing
GPA: 3.1
WE: Project Management (Non-Profit and Government)
Followers: 0

Kudos [?]: 19 [0], given: 36

Re: DS Work Problem [#permalink]  09 Nov 2011, 12:00
Thanks. Your explanation is so much clearer.

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Kelly

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Kudos [?]: 213 [0], given: 32

Re: Machines X and Y produce identical bottles at different [#permalink]  30 Nov 2011, 23:38
(1) x filled 30 x 4 = 120 bottles, but we do not know the what portion is 120. insufficient.

(2) y = 3b
x = 6b
total 9b
so 2 sufficient.
Ans. B
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Re: Machines X and Y produce identical bottles at different   [#permalink] 30 Nov 2011, 23:38
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