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Rahul kumar

· started a discussion

· 1 Months ago

this no show where

Question:

A and B can do a piece of work in 12 days, B and C in 15 days, C and A in 20 days. How long would A take separately to do the same work?

Options:
A)

10 days

B)

20 days

C)

30 days

D)

40 days

Solution:

Ans: (c)

(A+B)’s one day work =  112   

(B+C)’s one day work =  115   

(C+A)’s one day work =  120   

(A+B+C)’s one day work 

12×112+115+120   

12×1260=110   

If A do work alone, then,

A’s one day work = (A+B+C)’s one day work – (B+C)’s one day work

1/10 - 1/15 =(3-2)/30 =1/30 

Thus, A can complete the work in  = 30 days.

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