A can do a piece of work in 10 days, B can do the same in 30 days and C in 60 days. If A is assisted on alternate days by B and C, in how many days is the work finished?
- 4 days
- 5 days
- 6 days
- 7 days
- 8 days
The Usual Method
If A and B work together, of the work is completed.
If A and C work together, of the work is completed.
Hence if in 2 days, A & B and A & C work alternately, of the work is completed.
If of the work is completed in 2 days, to complete the whole work, it will take 8 days.
Estimated Time to arrive at the answer = 60 seconds.
Since B and C work on alternate days with A, then in every consecutive working days, A will work for both the days and B and C for 1 day each.
Hence, A will finish of the work in 2 days
B will finish of the work in 1 day
C will finish of the work in 1 day
Thus, in 2 consecutive days, of the work is done. Hence, it will take 4 such consecutive 2 days or 8 working days to finish the work.
Estimated Time to arrive at the answer = 15 seconds.