The number of days to finish a work by A is double the number of days to finish the work by B. The number of days to finish the work by C is half the number of days to finish the work by B. A can finish the work in 12 days. If B works on the 1st day, A works on the 2nd day and C works on the 3rd day, again B works on the 4th day and so on, then the work is finished in _____ days.
Show answer & explanation
Correct answer: D
Explanation
The correct answer is option 4 i.e. 5.5 .
A = 12 days → 1/12
B = 6 days → 1/6
C = 3 days → 1/3
Every 3 days work = 1/6 + 1/12 + 1/3 = 7/12
After 3 days: 7/12 done
Remaining: 5/12
Next:
Day 4 (B): +1/6 → 9/12
Day 5 (A): +1/12 → 10/12
Day 6 (C): needs 2/12 → Time = (2/12) ÷ (1/3) = ½ day
Total = 5.5 days