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# Working at a constant rate, a cook can create a batch of pasta in 20 m

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Math Expert
Joined: 02 Sep 2009
Posts: 58464
Working at a constant rate, a cook can create a batch of pasta in 20 m  [#permalink]

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18 Jan 2019, 01:13
00:00

Difficulty:

15% (low)

Question Stats:

79% (01:27) correct 21% (02:03) wrong based on 41 sessions

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Working at a constant rate, a cook can create a batch of pasta in 20 minutes. Another cook, working at a constant rate, can create the same batch of pasta in 10 minutes. If the two cooks work together but independently, how many hours will it take them to create 3 batches of pasta?

A 1/4
B 1/3
C 1/2
D 3/5
E 2

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Joined: 31 Oct 2013
Posts: 1468
Concentration: Accounting, Finance
GPA: 3.68
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Re: Working at a constant rate, a cook can create a batch of pasta in 20 m  [#permalink]

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18 Jan 2019, 03:50
Bunuel wrote:
Working at a constant rate, a cook can create a batch of pasta in 20 minutes. Another cook, working at a constant rate, can create the same batch of pasta in 10 minutes. If the two cooks work together but independently, how many hours will it take them to create 3 batches of pasta?

A 1/4
B 1/3
C 1/2
D 3/5
E 2

First cook takes 20 mins to create a batch of pasta.

Second cook takes 10 mins to create a batch of pasta.

They are working together to create 3 batches of pasta.

First cook = 1 batch ...........20 mins.

In this 20 mins second cook creates 2 batch of pasta.

Total : 3 batches.

20/60 = 1/3 hr.

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Re: Working at a constant rate, a cook can create a batch of pasta in 20 m  [#permalink]

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18 Jan 2019, 09:46
1
Bunuel wrote:
Working at a constant rate, a cook can create a batch of pasta in 20 minutes. Another cook, working at a constant rate, can create the same batch of pasta in 10 minutes. If the two cooks work together but independently, how many hours will it take them to create 3 batches of pasta?

A 1/4
B 1/3
C 1/2
D 3/5
E 2

combined rate:
1/20 + 1/10 = 3/20 * 60 = 9 or say 1/9 hours
1/9 * 3/1 = 1/3
IMO B
Re: Working at a constant rate, a cook can create a batch of pasta in 20 m   [#permalink] 18 Jan 2019, 09:46
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