Question

A,B&C can do a work in12,15&20 days respectively.They started working together but after 4 days A left.In how many days will B & C complete the work?

Answer 1

Hi there!
Here's the answer:

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A,B&C can do a work in12,15&20 days respectively.

=> In one day,

A will complete 1/12 th part of work
B will complete 1/15 th part of work
C will complete 1/20 th part of work

For simplicity, Express their each day work with same denominator(which is LCM of denominators of each)

{ Where LCM(12,15,20) = 60}

=> In one day,
A will complete 5/60 th part of work
B will complete 4/60 th part of work
C will complete 3/60 th part of work

At the end of fourth day,
A will complete 20/60 th part of work
B will complete 16/60 th part of work
C will complete 12/60 th part of work

Part of work completed = (20+16+12)/60
= 48/60

Part of Work remained = 12/60

In one day,
B and C can complete (4+3)/60 = 7/60 th part of work.

•°• It will take (12/60)/(7/60)
=(12/7)
= 1 5/7days

For B and C to complete the remaining work, it will take 1 5/7 days.

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