Pipes and Cistern
- There are two pumps to fill a tank with water. First pump can fill the empty tank in 8 hours, while the second in 10 hours. If both the pumps are opened at the same time and kept open for 4 hours, the part of tank that will be filled up is:
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As per the given in question , we have
Part of the tank filled in an hour by both pumps = 1 + 1 = 5 + 4 = 9 8 10 40 40
Correct Option: A
As per the given in question , we have
Part of the tank filled in an hour by both pumps = 1 + 1 = 5 + 4 = 9 8 10 40 40 ∴ Part of the tank filled in 4 hours = 4 × 9 = 9 40 10
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Two pipes A and B can fill a cistern in 37 1 minutes and 45 minutes respectively. Both 2
pipes are opened.The cistern will be filled just in half an hour, if the pipe B is turned off after :
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On the basis of given details in question ,
Pipe A fills the tank in 75/2 minutes.∴ Part of the tank filled by A in 30 minutes = 2 × 30 = 4 75 5 Remaining part = 1 - 4 = 1 5 5
Correct Option: D
On the basis of given details in question ,
Pipe A fills the tank in 75/2 minutes.∴ Part of the tank filled by A in 30 minutes = 2 × 30 = 4 75 5 Remaining part = 1 - 4 = 1 5 5
Now, 1 part is filled by pipe B in 45 minutes∴ 1 / 5 part is filled in = 45 × 1 = 9 minutes 5
Hence, the pipe B should be turned off after 9 minutes.
- A tank can be filled with water by two pipes A and B together in 36 minutes. If the pipe B was stopped after 30 minutes, the tank is filled in 40 minutes. The pipe B can alone fill the tank in
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Let the pipe B fill the tank in t minutes.
Part of the tank filled by pipes A and B in 1 minute = 1 36 ∴ Part of the tank filled by pipe A in 1 minute = 1 - 1 36 t
According to the question,30 × 1 + 40 
1 - 1 
= 1 t 36 t ⇒ 30 + 10 - 40 = 1 t 9 t
Correct Option: D
Let the pipe B fill the tank in t minutes.
Part of the tank filled by pipes A and B in 1 minute = 1 36 ∴ Part of the tank filled by pipe A in 1 minute = 1 - 1 36 t
According to the question,30 × 1 + 40 1 - 1 = 1 t 36 t ⇒ 30 + 10 - 40 = 1 t 9 t ⇒ 40 - 30 = 10 - 1 t t 9 ⇒ 10 = 1 ⇒ t = 90 minutes t 9
- A tap takes 36 hours extra to fill a tank due to a leakage equivalent to half of its inflow. The inflow can fill the tank in how many hours?
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Let the inflow fill the tank in t hours.
According to question ,
[leakage being half of inflow]∴ 1 - 1 = 1 t 2t 36 ⇒ 2 - 1 = 1 2t 36
Correct Option: D
Let the inflow fill the tank in t hours.
According to question ,
[leakage being half of inflow]∴ 1 - 1 = 1 t 2t 36 ⇒ 2 - 1 = 1 2t 36
⇒ 2t = 36⇒ t = 36 = 18 hours 2
- A tank can be filled by two pipes in 20 minutes and 30 minutes respectively. When the tank was empty, the two pipes were opened. After some time, the first pipe was stopped and the tank was filled in 18 minutes. After how much time of the start was the first pipe stopped?
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Let the first pipe be closed after t minutes .
According to question ,∴ t + 18 = 1 20 30 ⇒ t = 1 - 18 = 1 - 3 = 2 20 30 5 5 ⇒ t = 2 × 20 = 8 minutes; 5
Second method to solve this question :
Here, p = 20, q = 30, t = 18
[∵ first pipe is closed]Required time = 
p 1 - t 
q
Correct Option: B
Let the first pipe be closed after t minutes .
According to question ,∴ t + 18 = 1 20 30 ⇒ t = 1 - 18 = 1 - 3 = 2 20 30 5 5 ⇒ t = 2 × 20 = 8 minutes; 5
Second method to solve this question :
Here, p = 20, q = 30, t = 18
[∵ first pipe is closed]Required time = p 1 - t q Required time = 20 1 - 18 30 Required time = 20 × 12 = 8 minutes; 30
