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Re: If it would take one machine 10 minutes to fill a large production ord [#permalink]
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Since , Machine 1-M1 take 10 mins to fill the order
The work done by M1 in a min = 1/10
Machine 2- M2 take 12 mins to fill the same order
and work done by M2 in a min = 1/12

Total work done by M1 and M2 in a min = 1/10 + 1/12 = 11/60
Time needed for M1 and M2 to complete the order = 60/11 = 5 5/11

Answer C
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Re: If it would take one machine 10 minutes to fill a large production ord [#permalink]
Expert Reply
Hi All,

This question can be solved using the Work Formula:

Work = (A)(B)/(A+B) where A and B are the individual completion rates of the respective entities (for the same job).

We're told that one machine takes 10 minutes to complete a job and another machine takes 12 minutes to complete the same job. Plugging in those values gets us...

(10)(12)/(10+12) = 120/22 = 5 10/22 = 5 5/11 minutes

Final Answer:

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Re: If it would take one machine 10 minutes to fill a large production ord [#permalink]
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Top Contributor
Bunuel wrote:
If it would take one machine 10 minutes to fill a large production order and another machine 12 minutes to fill the same order, how many minutes would it take both machines working together, at their respective rates, to fill the order?

A. 4 1/60
B. 5
C. 5 5/11
D. 5 1/2
E. 11
PS21161


With most work questions, a useful approach is to assign a "nice" value to the total job.
We want a number that works well with the given numbers, 10 and 12

So, let's say the production order consists of making 120 widgets

It would take one machine 10 minutes to fill the production order
Rate = output/ time = 120/10 = 12 widgets per minute

It would take the other machine 12 minutes to fill the production order
Rate = output/ time = 120/12 = 10 widgets per minute

COMBINED rate of both machines = 12 + 10 = 22 widgets per minute

How many minutes would it take both machines working together, at their respective rates, to fill the order?
Time = output/rate = 120/22 = 60/11 = 5 5/11 minutes

Answer: C

Cheers,
Brent
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If it would take one machine 10 minutes to fill a large production ord [#permalink]
Bunuel wrote:
If it would take one machine 10 minutes to fill a large production order and another machine 12 minutes to fill the same order, how many minutes would it take both machines working together, at their respective rates, to fill the order?

A. 4 1/60
B. 5
C. 5 5/11
D. 5 1/2
E. 11


PS21161
FORMULA APPROACH

\(\frac{10*12}{10+12} = \frac{120}{22} => \frac{60}{11} = 5\frac{5}{11}\), Answer must be (C)
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If it would take one machine 10 minutes to fill a large production ord [#permalink]
Expert Reply
­Bread and butter rate question:

­
GMAT Club Bot
If it would take one machine 10 minutes to fill a large production ord [#permalink]
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