Pipes and Cistern Practice Questions with Answers and Solutions Set 01

Looking for the best way to master Pipes and Cistern questions for competitive exams? This post brings you 10 handpicked Pipes and Cistern practice questions with correct answers and detailed solutions. Perfect for SSC, Banking, Railways, and other government job exams, these questions will help you understand concepts like filling time, emptying time, efficiency, and combined work rates.

Pipes and Cistern problems are a common topic in quantitative aptitude sections of competitive exams. They involve concepts of rates of filling or emptying a tank, often with more than one pipe working together. Below are Pipes and Cistern practice questions with detailed step-by-step solutions.

Q1. A pipe can fill a tank in 6 hours. Another pipe can fill the same tank in 8 hours. How long will it take to fill the tank if both pipes are opened together?
A) 3 hrs 20 min
B) 3 hrs 25 min
C) 3 hrs 30 min
D) 3 hrs 36 min

Correct Option is: A) 3 hrs 20 min
Explanation: Pipe A’s rate = 1/6 tank per hour
Pipe B’s rate = 1/8 tank per hour
Combined rate = 1/6 + 1/8
= (4 + 3) / 24
= 7/24 tank per hour

Time taken = 1 / (7/24) = 24/7 hours
= 3 hrs 3/7 hrs = 3 hrs 20 min

Q2. A tank can be filled by a pipe in 4 hours. Due to a leak, it takes 5 hours to fill the tank. How long will it take for the leak alone to empty the tank?
A) 20 hrs
B) 18 hrs
C) 16 hrs
D) 15 hrs

Correct Option is: A) 20 hrs
Explanation: Filling rate = 1/4 tank per hour
Effective rate (with leak) = 1/5 tank per hour
Leak rate = 1/4 – 1/5 = (5 – 4) / 20
= 1/20 tank per hour
So, leak alone will empty the tank in 20 hours.

Q3. Two pipes can fill a cistern in 12 min and 15 min respectively. Both are opened together but after 3 minutes, the first pipe is closed. How much more time will the second pipe take to fill the tank?
A) 8.25 min
B) 9 min
C) 10 min
D) 12 min

Correct Option is: A) 8.25 min
Explanation: First pipe rate = 1/12 tank per min
Second pipe rate = 1/15 tank per min
In 3 minutes:
Water filled = 3 × (1/12 + 1/15)
= 3 × (5 + 4) / 60
= 27/60
= 9/20

Remaining = 1 – 9/20 = 11/20

Time by second pipe
= (11/20) ÷ (1/15)
= (11/20) × 15
= 165/20 = 8.25 min

Q4. A tap can fill a tank in 10 hours. Another tap can empty it in 15 hours. If both are opened together, in how many hours will the tank be filled?
A) 25 hrs
B) 30 hrs
C) 40 hrs
D) 50 hrs

Correct Option is: B) 30 hrs
Explanation: Filling rate = 1/10 tank per hour
Emptying rate = 1/15 tank per hour
Net rate = 1/10 – 1/15 = (3 – 2) / 30 = 1/30 tank per hour
Time taken = 30 hours

Q5. A cistern has two pipes. One can fill it in 5 hrs and the other in 6 hrs. A waste pipe can empty it in 12 hrs. If all three pipes are open, how long will it take to fill the tank?A) 60/17 hrs
B) 50/17 hrs
C) 65 hrs
D) 83 hrs

Correct Option is: A) 60/17 hrs
Explanation: Filling rates: 1/5 + 1/6 = (6 + 5) / 30 = 11/30
Emptying rate = 1/12

Net rate = 11/30 – 1/12
= (44 – 10) / 120
= 34/120
= 17/60 tank per hour

Time = 1 / (17/60) = 60/17 hrs

Q6. A tap can fill a tank in 8 hrs and another can fill it in 12 hrs. The tank has a leak that can empty the full tank in 24 hrs. If all three are opened, how long will it take to fill the tank?A) 4 hrs
B) 5 hrs
C) 6 hrs
D) 7 hrs

Correct Option is: C) 6 hrs
Explanation: Filling rates: 1/8 + 1/12 = (3 + 2) / 24 = 5/24
Leak rate = 1/24

Net rate = 5/24 – 1/24 = 4/24 = 1/6 tank per hour
Time = 6 hrs

Q7. Two taps can fill a cistern in 24 min and 32 min respectively. If both are opened together, how long will it take to fill the cistern?A) 13 5/7 min
B) 14 min
C) 14 5/7 min
D) 15 min

Correct Option is: A) 13 5/7 min
Explanation: Rate = 1/24 + 1/32
= (4 + 3) / 96
= 7/96 tank per min

Time = 96/7 min = 13 min + (5/7) min
= 13 5/7 min.

Q8. A pipe can fill a tank in 9 hrs. Due to a small leak, it took 9 hrs 36 min to fill. How long would the leak take to empty the full tank?A) 144 hrs
B) 200 hrs
C) 210 hrs
D) 216 hrs

Correct Option is: A) 144 hrs
Explanation: Filling rate = 1/9 tank per hour
Effective rate = 1 / 9.6 hours = 5/48 tank per hour
Leak rate = 1/9 – 5/48 = (16 – 15) / 144 = 1/144 tank per hour
So, leak empties the tank in 144 hrs

Q9. A tank can be filled by three pipes in 4, 6, and 8 hrs respectively. How long will it take if all three are opened together?A) 24/13 hrs
B) 2 hrs 10 min
C) 2 hrs 20 min
D) 2 hrs 30 min

Correct Option is: A) 24/13 hrs
Explanation: Rate = 1/4 + 1/6 + 1/8 = (6 + 4 + 3) / 24 = 13/24 tank per hour
Time = 24/13 hrs

Q10. Two pipes can fill a tank in 16 min and 20 min. Both are opened together but after 4 min, the first pipe is closed. How much more time will the second take to fill the rest?A) 12 min
B) 12 min
C) 14 min
D) 15 min

Correct Option is: B) 12 min
Explanation: Rates: 1/16 + 1/20 = (5 + 4) / 80 = 9/80
In 4 min: Water filled = 4 × (9/80) = 36/80 = 9/20
Remaining = 1 – 9/20 = 11/20
Time by second pipe = (11/20) ÷ (1/20) = 11 min

Pipes and Cistern problems require strong understanding of combined rates and time calculations. Practice regularly to improve speed and accuracy.