This set of Aptitude Questions and Answers (MCQs) focuses on “Pipes and Cistern”. These questions are beneficial for various competitive exams, placement interviews, and entrance tests.
1. 3 pipes A, B and C can fill a tank in 30 minutes, 40 minutes, and 120 minutes, respectively. If all the pipes are opened together, how much time is required to fill the tank?
a) 12 minutes
b) 15 minutes
c) 18 minutes
d) 20 minutes
View Answer
Explanation: The time taken by the pipes individually = 30 minutes, 40 minutes, and 120 minutes.
Let the capacity of the tank be 120 litres.
The efficiency of the pipes = 120 / 30, 12 / 40, 120 / 120 = 4, 3, 1 respectively
The efficiency of all the pipes together = 4 + 3 + 1 = 8
The time taken now = 120 / 8 = 15 minutes
2. 3 pipes can fill a bucket in 20minutes, 30 minutes and 60 minutes, respectively. If all the pipes are opened for 5 minutes what percentage of the tank will be filled.
A) 50%
b) 60%
c) 75%
d) 100%
View Answer
Explanation: Let the capacity of the tank be = 60 litres.
The efficiencies of the pipes = 60 / 20 = 3, 60 / 30 = 2, 60 / 60 = 1 litre per minute
The total efficiency = 3 + 2 + 1 = 6 litres per minute
The amount of tank filled after 5 minutes = 6 * 5 = 30 litres = 50% of the total capacity that was assumed to be 60.
3. 3 pipes A, B and C can fill a tank in 50 minutes, 120 minutes, and 60 minutes, respectively. If all the pipes are opened together, how much time is required to fill 27% of the tank?
a) 2 minutes
b) 4 minutes
c) 6 minutes
d) 10 minutes
View Answer
Explanation: Let the capacity of the tank be 600 litres.
The efficiencies of the pipes = 600 / 50, 600 / 120, 600 / 60 = 12, 5, 10 litres
The total efficiency of the pipes = 12 + 5 + 10 = 27 litres
To fill 27% of the tank that is 27 * 600 / 100 = 162 litres
162 / 27 = 6 minutes
4. 3 pipes can fill a tank in 20 minutes, 90 minutes and 180 minutes, respectively. If all the pipes are opened at once what percentage of the tank will be filled in 10 minutes?
a) 50%
b) 55%
c) 60%
d) 66.66%
View Answer
Explanation: Let the capacity of the tank be 180 litres.
The efficiency of the pipes = 180 / 20, 180 / 90, 180 / 180 = 9, 2, 1
The total efficiency of the pipes = 9 + 2 + 1 = 12
The quantity of water flow through all the pipes in 10 minutes = 12 * 10 = 120 litres
The percentage required = 120 / 180 * 100 = 66.66%
5. There are three pipes connected to a tank. The first two can fill the tank in 20 minutes and 30 minutes, respectively. The third pipe can empty the entire tank in 5 minutes. If all the pipes are opened simultaneously, what time will it take to empty the tank?
a) 8.55 minutes
b) 8.56 minutes
c) 8.57 minutes
d) 8.58 minutes
View Answer
Explanation: Let the capacity of the tank be 60 litres.
The efficiency of the pipes = 60 / 20, 60 / 30 and 60 / 5 respectively.
The efficiency = 3, 2, 12 respectively.
The relative efficiency when all the pipes are opened simultaneously = 3 + 2 – 12 = – 7
The time taken to empty the tank = 60 / 7 minutes = 8.57 minutes.
6. Three pipes are opened for 8 minutes each one after the other. The first two pipes can fill a tank in 20 minutes and 40 minutes, respectively. If the third pipe can empty the tank in 120 minutes, find the amount of water filled in the tank after 24 minutes. The tank is 480 litres.
a) 160 litres
b) 188 litres
c) 224 litres
d) 256 litres
View Answer
Explanation: The capacity of the tank o 480 litres.
The efficiencies of the pipes = 480 / 20, 480 / 40 and 480 / 120 respectively.
The efficiencies of the pipes = 24, 12, 4 respectively.
The relative efficiency = 24 + 12 – 4 = 32 litres per minute.
The time period the pipes were open for = 8 minutes each.
The water flowed through the pipes = 32 * 8 = 256 litres.
7. 2 pipes can empty a tank in 70 minutes and 140 minutes, respectively. If a third pipe can fill the tank in 7 minutes, find the time required to fill the tank if all the pipes are opened simultaneously.
a) 7.23 minutes
b) 8.23 minutes
c) 8.57 minutes
d) 8.88 minutes
View Answer
Explanation: Let the capacity of the tank be 140 litres.
The efficiency of the pipes = 140 / 70, 140 / 140 and 140 / 7 respectively.
The efficiency of the pipes = 2, 1, 20 respectively.
The relative efficiency = 20 – 1 – 2 = 20 – 3 = 17 litres per minute.
The time taken = 140 / 17 = 8.23 minutes.
8. A pipe can fill a tank in 3 minutes if other two pipes can empty the tank in 2 minutes and 5 minutes respectively, find the time to empty the tank if all the pipes are opened simultaneously.
a) 2.27 minutes
b) 2.72 minutes
c) 7.27 minutes
d) 7.72 minutes
View Answer
Explanation: Let the capacity of the tank be 30 litres.
The efficiency of the pipes = 30 / 3, 30 / 2 and 30 / 5 litres respectively.
The efficiencies of the pipes = 10, 15, 6 respectively.
The relative efficiency to empty the tank = 15 + 6 – 10 = 11 litres per minute.
The time required = 30 / 11 = 2.72 minutes.
9. A pipe can empty a tank in 2 minutes. Another pipe can empty the tank in 12 minutes, and a third pipe can fill the tank in 22 minutes. What is the time required to empty the tank if all the pipes are opened simultaneously?
a) 1.85 minutes
b) 1.95 minutes
c) 2.05 minutes
d) 2.15 minutes
View Answer
Explanation: Let the capacity of the tank be 132 litres.
The efficiency of the pipes = 132 / 2, 132 / 12 and 132 / 22 respectively.
The efficiency of the pipes = 66, 11 and 6 respectively.
The relative efficiency to empty the tank = 66 + 11 – 6 = 71 litres per minute.
The time required to empty the tank = 132 / 71 = 1.85 minutes.
10. If 3 taps are opened simultaneously, the tank fills in 15 minutes. The first two taps are combined 50% more efficient than the third one. Find the time taken by the third pipe to fill the tank.
a) 23.5 minutes
b) 32.5 minutes
c) 37.5 minutes
d) 42.5 minutes
View Answer
Explanation: Let the capacity of the tank be 15 litres.
The efficiency of the three pipes together = 15 / 15 = 1
The first two pipes are 50% more efficient than the third pipe.
Let the efficiency of the third pipe be x.
The efficiency of the first 2 pipes combined = x + 50% of x = 1.5x
The efficiency of all the pipes combined = 2.5x
2.5x = 1
X = 1 / 2.5 = 0.4
The time required by the third pipe to fill the tank alone = 15 / 0.4 = 37.5 minutes.
More Aptitude Questions and Answers on Pipes and Cistern:
- Pipes and Cistern Questions (Set 2)
- Pipes and Cistern Questions (Set 3)
- Pipes and Cistern Questions (Set 4)
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