A, B and C can separately complete a work in 20, 25 and 30 days, respectively. If A works on the first day alone, B on second day alone and C on the third day alone, and this sequence goes on further, in how many days will the entire work be finished?
Show answer & explanation
Correct answer: D
Explanation
The correct answer is option 4 i.e. 24.
Work in 3 days (A + B + C) = 1/20 + 1/25 + 1/30
⇒ 15/300 + 12/300 + 10/300 = 37/300
After 8 cycles (24 days) = 8 × 37/300 = 296/300
Remaining work = 1 − 296/300 = 4/300 = 1/75
Time = Work/Rate = (1/75)/(1/20) = 20/75 = 4/15 day
Total time = 24 + 4/15 = 364/15 = 24 days