Question

A and B can do a piece of work in 15 days: B and C in 10 days while C and A in 12
days. In how many days will C finish the work alone?
(a) 24 days (b) 30 days (c) 15 days (d) 8 days​

Answer 1

Answer:

A + B = 10 , B+C = 12 , A+C = 15

Now finding LCM which we would consider as total work , LCM = 60 = total work

Now , Efficiency of A + B in 1 day = 60/10 so 6.

Similarly , B+C = 5 and A+C = 4.

add all of the efficiency

(A+B) + ( B+C) + ( A+C ) = 5+4+6

2 ( A+ B+ C ) = 15

A+B+C = 15/2 , THIS IS EFFICIENCY

NOW, TIME = TOTAL WORK / EFFICIENCY

TIME = 60* 2 /15 = 8 days.