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Wendy can build a birdhouse in 15 hours and Miguel can build an identi

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Wendy can build a birdhouse in 15 hours and Miguel can build an identi  [#permalink]

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New post 03 Jul 2018, 00:09
00:00
A
B
C
D
E

Difficulty:

  5% (low)

Question Stats:

95% (00:52) correct 5% (01:15) wrong based on 65 sessions

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Wendy can build a birdhouse in 15 hours and Miguel can build an identical birdhouse in 10 hours. How many hours will it take Wendy and Miguel, working together at their respective constant rates, to build a birdhouse? (Assume that they can work on the same birdhouse without changing each other’s work rate.)

(A) 5
(B) 6
(C) 7
(D) 8
(E) 9

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Re: Wendy can build a birdhouse in 15 hours and Miguel can build an identi  [#permalink]

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New post 03 Jul 2018, 00:37
Bunuel wrote:
Wendy can build a birdhouse in 15 hours and Miguel can build an identical birdhouse in 10 hours. How many hours will it take Wendy and Miguel, working together at their respective constant rates, to build a birdhouse? (Assume that they can work on the same birdhouse without changing each other’s work rate.)

(A) 5
(B) 6
(C) 7
(D) 8
(E) 9


Combining several rates of work is often done by reducing them to work per unit time.
This is what we'll do, a Precise approach.

Wendy builds 1 birdhouse in 15 hours so 1/15 birdhouses per hour.
Miguel builds 1 birdhouse in 10 hours so 1/10 birdhouses per hour.
Together they build 1/10 + 1/15 = 25/150 = 1/6 birdhouses per hour.
Then they need a total of 6 hours.

(B) is our answer.
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Re: Wendy can build a birdhouse in 15 hours and Miguel can build an identi  [#permalink]

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New post 03 Jul 2018, 02:10
Wendy takes 15 hours. Therefore she does 6.67% work in 1 hour.
Miguel takes 10 hours. Therefore he does 10% work in 1 hour.
Total work = 100%
Total time = 100/(10+6.67) = 6 hours
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Re: Wendy can build a birdhouse in 15 hours and Miguel can build an identi  [#permalink]

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New post 03 Oct 2018, 00:26
Rate of work of Wendy=1/15 (work/hr)
Rate of work of Miguel=1/10 (work/hr)
Rate of work of Wendy & Miguel together=1/15+1/10= 25/150= 1/6 (work/hr)
So, time taken by Wendy & Miguel together to finish job = 6 hrs

Ans-(B)
GMAT Club Bot
Re: Wendy can build a birdhouse in 15 hours and Miguel can build an identi   [#permalink] 03 Oct 2018, 00:26
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Wendy can build a birdhouse in 15 hours and Miguel can build an identi

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