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# Pipes and Cisterns Questions for RRB JE:

Download Pipes and Cisterns Questions & Answers PDF for RRB JE exam. RRB JE Questions based on asked questions on pipes and cisterns from previous exam papers, very important for the Railway JE exam.

Question 1: A pipe of diameter ‘d’ can drain a certain water tank in 40 minutes. The time taken by a pipe of diameter ‘2d’ for doing the same job is :

a) 50 Min

b) 10 Min

c) 20 Min

d) 80 Min

Question 2: A pipe can fill a tank in 15 hours. Another pipe can empty the tank in 20 hours. If both the taps are opened, how long will it take for a half-full tank to become full?

a) 45 hours

b) 24 hours

c) 30 hours

d) 36 hours

Question 3: Pipe A fills up a tank in 20 hr and a hole empty the tank in 30 hr, if both of them working together then how long will it take to fill up the tank?

a) 30 hr

b) 40 hr

c) 60 hr

d) 80 hr

Question 4: The inlet to a tank can fill it in 4 hours while the outlet to the tank can empty it in 5 hours Both the pipes were opened at 9 Am but after sometime the outlet was closed and it is observed that the tank was full at 5 PM. At what time was the outlet closed ?

a) 1 PM

b) 2 PM

c) 3 PM

d) 4 PM

Question 5: A pipe fills a tank in 120 minutes and another drill empties it in 180 minutes. If both of them are working together than how long will it take to fill the pipe?

a) 320 min.

b) 340 min.

c) 350 min

d) 360 min

Question 6: A pipe can fill a tank in 6 hours and an outlet to the tank can fill it in 8 hours. If Both the valves were opened at 8:00 am in the morning but after sometime outlet valve was closed. It is seen that tank was full at 5:00 pm. At what time was outlet valve closed?

a) 1:00 pm

b) 2:00 pm

c) 11:00 am

d) 12:00 pm

Question 7: Pipe A takes 4 hours to fill a tank. Pipe B takes 6 hours to empty the same tank when full. If both the pipes are opened at the same time when the tank is empty, how many hours will it take for the tank to fill?

a) 10

b) 8

c) 12

d) 15

Question 8: A pipe can fill a tank in 12 hours. By mistake another pipe that empties the tank is left open and the tank is filled in 16 hours. If the tank is fill, how much time will the second pipe take to empty it?

a) 48 minutes

b) 48 days

c) 2.01 days

d) 48 hours

Question 9: Pipe A is an inlet pipe that can fill an empty cistern in 8.7 hours. Pipe B can drain a filled cistern in 5.8 hours. When the cistern was filled the two pipes are opened one at a time for an hour each, starting with Pipe B. How long will it take for the cistern to be empty?

a) 32 hours 16 minutes

b) 30 hours 48 minutes

c) 32 hours

d) 31 hours

Question 10: Inlet Pipe A can fill a cistern in 35 hours while outlet Pipe B can drain the filled cistern in 40 hours. The two pipes are opened together when the cistern is empty, but the outlet pipe is closed when the cistern is three-fifths full. How many hours did it take in all to fill the cistern?

a) 185

b) 182

c) 184

d) 180

Question 11: Pipes A and B, when working together, can fill an empty tank in 24 hours. They work together for 8 hours and then B is stopped but A continued to work. It took a total of 28 hours to fill the tank. How long would it take A to fill the empty tank alone?

a) 30 hours

b) 29 hours

c) 28 hours

d) 31 hours

Question 12: Pipe A can fill an empty cistern in 5 hours while Pipe B lakes 6.25 hours to fill it. The two pipes are opened simultaneously when the cistern is empty, but Pipe B is turned off after some time as a result of which the cistern is filled in 3.4 hours. For how many hours was Pipe B open?

a) 1.5

b) 1

c) 2

d) 2.5

Question 13: Pipe C and D alone can fill a tank in 4 and 5 hours, respectively. If pipe C is closed after 3 hours and at the same time pipe D is opened. in how many hours will the tank get filled?

a) 0.8

b) 1.25

c) 1

d) 1.5

Question 14: Pipe A can fill a tank in 2 hrs and pipe B can empty the tank in 2.5 hrs, then find the time in which the tank would be filled if both pipes are opened at the same time ?

a) 10 hrs

b) 12 hrs

c) 8 hrs

d) 6 hrs

Question 15: Two pipes P and Q can empty a tank in 15 minutes and 30 mins respectively, then find the time taken to empty half the tank if both are opened at the same time ?

a) 10 min

b) 8 min

c) 6 min

d) 5 min

Question 16: Two pipes A and B can fill a tank in 4 hrs and 8 hrs respectively. Both the pipes are opened simultaneously, find the time needed to fill the tank?

a) $3\frac{1}{3}$ hrs

b) $3\frac{2}{3}$ hrs

c) $2\frac{2}{3}$ hrs

d) $2\frac{1}{3}$ hrs

Question 17: Pipe A can fill a tank in 2 hrs, Pipe B can fill the same tank in 3 hrs, In how many hours both pipes together can fill the tank ?

a) $1\frac{2}{5}$

b) $1\frac{1}{5}$

c) $1\frac{3}{5}$

d) $1\frac{4}{5}$

Question 18: Pipe A can fill a tank in 4 hrs whereas pipe B can empty the tank in 10 hrs, Find the total time in which tank will be filled if both pipes are opened ?

a) 5hrs 45mins

b) 5hrs 40mins

c) 6hrs 45mins

d) 6hrs 40mins

Question 19: One of the two inlet pipes works twice as efficiently as the other. The two, working alongside a drain pipe that can empty a cistern all by itself in 12 hours, can fill the empty cistern in 12 hours. How many hours will the less efficient inlet pipe take to fill the empty cistern by itself?

a) 9

b) 15

c) 12

d) 18

Question 20: Pipe A is an inlet pipe that can fill an empty cistern in 69 hours. Pipe B can drain the filled cistern in 46 hours. When the cistern was filled the two pipes are opened one at a time for an hour each, starting with Pipe B. how long will it take for the cistern to be empty?

a) 11 days 10 hours

b) 11 days 7 hours

c) 11 days 12 hours

d) 1 days 13 hours

Question 21: A water tank is $\frac{2}{5}$ th full. Inlet A can fill the tank in 12 minutes while an outlet pipe B can empty it in 6 minutes. If both the pipes are open, how long will it take to empty or fill the tank completely?

a) It fills in 4.8 min

b) It empties in 4.8 min

c) It fills in 5.6 min

d) It empties in 5.6 min

Question 22: Pipes A and C can fill an empty cistern in 7 and 10.5 hours, respectively while Pipe B can drain the filled cistern in 5.25 hours. If the three pipes are turned on together when the cistern is empty, how many hours will it take for the cistern to be $\frac{2}{3}$ full?

a) 121

b) 12

c) 14

d) 15.75

Question 23: Pipes A, B and C are attached to an empty cistern. While the first two can fill the cistern in 6.6 and 16.5 hours respectively, the third can drain the cistern, when filled, in 9.9 hours. If all the three pipes are opened simultaneously when the cistern is three-fifths full, how many hours will be needed to fill the cistern?

a) 3.5

b) 4

c) 3.6

d) 3.75

Question 24: Two pipes A and B can fill an empty cistern in 1.8 and 2.7 hours, respectively. Pipe C can drain the entire cistern in 4.5 hours when no other pipe is in operation. Initially when the cistern was empty Pipe A and Pipe C were turned on. After a few hours Pipe A was turned off and Pipe B was turned on instantly. In all it took 5.5 hours to fill the cistern. For how many hours was Pipe B turned on?

a) 5

b) 4.5

c) 3

d) 2.7

Question 25: A water tank is filled in 5 hours by three pipes X, Y and Z the pipe Z is thrice as fast as Y and Y is twice as fast as X. How much time will pipe X alone take to fill the water tank?

a) 60 hrs

b) 45 hrs

c) 40 hrs

d) 35 hrs

The time of flow of water through the pipes is inversely proportional to the area of the pipes.

The ratio of area of the two pipes are

=$\frac{\pi \times (2D)^{2}}{\pi \times (D)^{2}}$=4:1

Thus, the time taken by the larger pipe will be one-fourth of the smaller pipe.

Hence, the time taken by the larger pipe is =40/4=10.

Time taken to fill an empty tank when both the pipes are open = $\frac{1}{1/15 – 1/20}$ = 60 hours
So, time taken to fill a half-empty tank = 60/2 = 30 hours

In 1 hour pipe A will fill = $\frac{1}{20}$ part of the tank
In 1 hour hole will empty = $\frac{1}{30}$ part of the tank
If they are working together then in 1 hour part of tank filled will be =
$\frac{1}{20}$ – $\frac{1}{30}$ = $\frac{10}{600}$
Hence, tank will be filled in 60 hr

Let the outlet be open for x hours.

Let there be 100 units of water in the tank.

So, the speed of inlet is 25 units per hour and speed of the outlet is – 20 units per hr.

Let them be open for x hours. So, the total tank filled is 25 x – 20x =5x

For 8 – x hours the inlet is open. So, units of water = (8-x)*25

But that sum = 100

5x + 200 – 25 x = 100

20 x = 100

So, x = 5 hours. ie till 2 PM

In 1 min. part of tank filled = $\frac{1}{120}$
In 1 min. part of tank getting empty = $\frac{1}{180}$
In 1 min., when both of them working together, part of tank filled = $\frac{1}{120}$ – $\frac{1}{180}$ = $\frac{1}{360}$
Hence, it will take 360 min. to fill the tank.

Work done in an hour when both pipe were opened = $\frac{1}{6} – \frac{1}{8} = \frac{1}{24}$

Let’s say after x hours outlet pipe was closed, so total tank filled in that time = $\frac{x}{24}$
After that for remaining (9-x) hours, tank filled = $\frac{(9-x)}{6}$
Hence, $\frac{x}{24}$ + $\frac{(9-x)}{6}$ = 1
Now after solving for x, x=4 hours

Let the capacity of tank = LCM of 2 and 2.5 = 10 units

Filling efficiency of pipe A = 10/2 = 5 units/hr

Emptying efficiency of pipe B = 10/2.5 = 4 units/hr

If both pipes are opened,

The tank will be filled in 10/(5-4) = 10/(1) = 10 hrs

So the answer is option A.

Let the capacity of tank = LCM of 15 & 30 = 30 units

Efficiency of pipe P = 30/15 = 2 units/min

Efficiency of Pipe Q = 30/30 = 1 unit/min

Both pipes together can empty the half of the tank in 15/(2+1) = 15/3 = 5 mins

So the answer is option D.

Let Total capacity of tank = LCM of 4 and 8 = 8

Efficiency of A = 8/4 = 2

Efficiency of B = 8/8 = 1

Tank can be filled by both pipes in 8/(2+1) hrs = 8/3 hrs = $2\frac{2}{3}$ hrs

So the answer is option C.

Let the capacity of tank = LCM of 2&3 = 6 units

Efficiency of pipe A = 6/2 = 3

Efficiency of pipe B = 6/3 = 2

Both together can fill the tank in $\frac{6}{2+3} hrs = \frac{6}{5} hrs = 1\frac{1}{5}hrs$

So the answer is option B.

Let the capacity of tank = LCM of 4 & 10 = 20 units

Efficiency of A = 20/4 = 5 units/hr

Efficiency of B = 20/10 = 2 units/hr

Effective work = 5 – 2 = 3 units/hr

So tank will be filled in $20/3 = 6\frac{2}{3}hrs = 6 hrs 40 mins$

So the answer is option D.