27. A and B can do a piece of work in 12 days; Band C can do it
in 15 days ; A and C can do it in 20 days. In how many days will A, Band' C finish it, working all together?Also ,find the number of days taken by each to finish it working alone.
A.30,20,60 B.20,30,60
C.60,20,30 D.20,30,60
Answer:
(A+B)'s 1 day's work =1/12; (B+C)'s 1 day's work = 1/15
and (A + C)'s 1 day's work = 1/20
Adding, we get: 2 (A + B + C)'s 1 day's work =(1/12 + 1/15 + 1/20)= 1/5
:. (A + B + C)'s 1 day's work =1/10
Thus, A, Band C together can finish the work in l0 days.
Now, A's 1 day's work
= [(A + B + C)’s 1 day's work] - [(B + C)'s 1 day's work]
=(1/10 – 1/15) = 1/30
:. A alone can finish the work in 30 days.
Similarly, B's 1 day's work =(1/10 – 1/20)= 1/20
:. B alone can finish the work in 20 days.
And, C's 1 day's work=(1/10 – 1/12)= 1/60 .
:. C alone can finish the work in 60 days.
