# A can do a work in 4 hours;B and C together can do the same work in 3 hours,while A and C together can do it in 2 hours.How long will B alone take to do it.

2
by thirumalai

2014-12-05T12:32:16+05:30
A can work in one hour 1/4 of work.
B&C  in one hour can do 1/3 of work
A&C  in hour can do 1/2 of work
C in one hour produces= (1/2)-1/4=1/4 work
⇒ B in one hour produces=(1/3)-1/4 =1/12 work
Hence B will take 1/(1/12) = 12 hours to complete work.
2014-12-05T13:21:01+05:30

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A can do  1/4 th of work in 1 hour
B + C can do 1/3 rd of work in 1 hour
A + C  can do 1/2 of work in 1 hour

A+ B + C  can do  1/4+1/3 of work in 1 hour,  ie.,  7/12 th of work in  1 hour

So B can do what (A+B+C) do  -  what (A+C) do in 1 hour
ie.,  7/12 - 1/2
= 1/12 th of work in 1 hour

hence B will do  work in 12 hours.