A pump usually fills a tank in 10 hours but due to a hole in the tank it took…
2023
A pump usually fills a tank in 10 hours but due to a hole in the tank it took 12 hours to fill the tank. If the tank is full, how much time will it take to drain the whole tank ?
- A.
50 hours
- B.
45 hours
- C.
55 hours
- D.
60 hours
Attempted by 9 students.
Show answer & explanation
Correct answer: D
Solution: Find the hole's draining rate from the pump and net filling times.
The pump fills the tank in 10 hours, so the pump's filling rate is 1/10 tank per hour.
With the hole, the tank takes 12 hours to fill, so the net filling rate (pump minus leak) is 1/12 tank per hour.
The hole's draining rate = pump rate − net filling rate = 1/10 − 1/12 = 1/60 tank per hour.
Therefore, the hole alone would drain the full tank in 60 hours.