Aptitude Pipes and Cisterns Test Paper 1
1) A pipe can fill a tank in 6 hours and another pipe can empty the tank in 12 hours. If both the pipes are opened at the same time, the tank can be filled in
- 10 hours
- 12 hours
- 14 hours
- 16 hours
Correct answer; option (B)
Answer with explanation:
Part of the tank filled in one hour =
Part of the tank emptied in one hour =
Net part of the tank filled in one hour;
= –
Part of the tank can be filled in one hour.
∴ The tank will be filled completely in 12 hours.
Solution 2:
Apply formula; = 
X = 6 hours and Y = 12 hours
∴ 
= 12 hours
2) Three pipes A, B and C can fill a cistern in 8 minutes,12 minutes and 16 minutes respectively. What is the time taken by three pipes to fill the cistern when they are opened together?
- 3.7 minutes
- 4 minutes
- 4.5 minutes
- 5 minutes
Correct answer; option (A)
Answer with explanation:
Part of the tank filled by A in one minute = 
Part of the tank filled by B in one minute =
Part of the tank filled by C in one minute = 
Net part of the tank filled by A+B+C in one minute;
= + +
=
Part of the cistern is filled in one minute.
∴ The whole tank will be filled in 
= 3.7 minutes
3) Two pipes can fill a tank in 6 hours and 8 hours respectively. A third pipe can empty the same tank in 12 hours. If all the pipes start working together, how long it will take to fill the tank?
- 4 hours
- 4.5 hours
- 4.8 hours
- 5.2 hours
Correct Option (C)
Answer with explanation:
Part of the tank filled by two pipes in one hour = +
Part of the tank emptied by the third pipe in one hour =
∴ Net part of the tank filled in one hour = + –
= 
Part of tank can be filled in one hour
∴ The whole tank will be filled in 
= 4.8 hours
4) A tank can be filled in 10 hours. After a leak in its bottom, it takes 12 hours to fill the tank. Find the time taken by the leak to empty the full tank?
- 45 hours
- 60 hours
- 50 hours
- 55 hours
Correct Option (B)
Answer with explanation:
Part of the tank filled in one hour before the leak = 
Part of the tank filled in one hour after the leak =
Part of the tank emptied in one hour by the leak = –
part of tank will be emptied in one hour by the leak
∴ The full tank will be emptied by the leak in 60 hours.
Solution 2:
Apply formula; = 
X = 10 hours
Y = 12 hours
∴ 
= 60 hours
5) Two pipes can fill a tank in 10 and 14 minutes respectively. A third pipe can empty the tank at the rate of10 liters/minute. If all the pipes working together can fill the empty tank in 8 minutes,what is the capacity of the tank?
- 210 liters
- 215.4 liters
- 220 liters
- 225.4 liters
Correct answer; option (B)
Answer with explanation:
Let the capacity of the tank is X liters.
Part of the tank filled by two pipes in one minute = 1/10 + 1/14
10 liters is emptied in 1 minute
X liters will be emptied in X/10 minutes
In X/10 minutes the whole tank will be emptied.
In one minute 10/X part of the tank will be emptied.
As per question;
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