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Work Rate

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Work Rate

by jainrahul1985 » Sat Jul 25, 2009 6:18 am
Working together at their respective rates, machine A, B, and C can finish a certain work in 8/3 hours. How many hours will it take A to finish the work independently?
(1) Working together, A and B can finish the work in 4 hours.
(2) Working together, B and C can finish the work in 48/7 hours.

Please solve this question for me
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by aksravs » Sat Jul 25, 2009 7:49 am
IMO B
STMT2 GIVES US 1/B+1/C. THIS CAN BE SUBSTITUTED IN 1/A+1/B+1/C= 7/48 FROM THE STEM.

WHAT IS THE OA?
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by PussInBoots » Sat Jul 25, 2009 4:57 pm
1/a + 1/b + 1/c = 1 / (8/3)

1/b + 1/c = 1 / (40/7)

Find 1/a, that's rate of work / hour. You'll get 1/5, hence 5 hours
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by nplaneta » Sat Jul 25, 2009 7:01 pm
[EDIT - REMOVED BY THE USER]
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by anuragkundargi » Thu Dec 21, 2017 8:09 am
Work is 1 Unit

Let the rate of A= Ra , rate of B = Rb, rate of C= Rc

Combined Rate= Ra+ Rb + Rc

Rate= Work/ Time

Time= Work/ Rate = 1/Ra+ Rb + Rc =8/3

Ra+ Rb + Rc =3/8...............(1)

Also from 2nd statement,

1/Rb + Rc =48/7

Rb + Rc =7/48...........(2)

Substituting (2) in (1), we get

Ra + 7/48= 3/8

Ra=11/48

Time taken by A alone = Work/ Ra
= 1/(11/48)
=48/11
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