Two pipes can fill a tank in 20 and 30 minutes. If the tank is perfect. But…
2024
Two pipes can fill a tank in 20 and 30 minutes. If the tank is perfect. But there is a hole in the tank that can empty it in 60 minutes. If both the pipes are opened simultaneously, how long will it take to fill the tank ?
- A.
30 minutes
- B.
10 minutes
- C.
15 minutes
- D.
20 minutes
Attempted by 8 students.
Show answer & explanation
Correct answer: C
Answer: 15 minutes
Explanation:
Rate of first pipe: 1/20 of the tank per minute.
Rate of second pipe: 1/30 of the tank per minute.
Hole drains: 1/60 of the tank per minute (subtract this).
Net filling rate = 1/20 + 1/30 - 1/60 = (3 + 2 - 1)/60 = 4/60 = 1/15 tank per minute.
Time to fill = 1 ÷ (1/15) = 15 minutes.