Pipes and Cisterns - Aptitude Questions and Answers

Pipes and Cisterns Questions and Answers

Learn and practice the chapter "Pipes and Cisterns" with these solved Aptitude Questions and Answers. Each question in the topic is accompanied by a clear and easy explanation, diagrams, formulae, shortcuts and tricks that help in understanding the concept.

Use of Pipes and Cisterns Questions

The questions and examples given in this section will be useful to all the freshers, college students and engineering students preparing for placement tests or any competitive exam like MBA, CAT, MAT, SNAP, MHCET, XAT, NMAT, GATE, Bank exams - IBPS, SBI, RBI, RRB, SSB, SSC, UPSC etc.

Practice with this online test to crack your placements and entrance tests!
1. I have two inlet pipes in my tank. Pipe P is diametrically bigger than Q and can fill a tank alone in 22 hours while Pipe Q takes 11 hours longer than Pipe P to fill the tank. If I open both the inlet pipes together, how long will they take to fill the tank?

a.19hours
22
b. 11hours
11
c. 131hours
5
d. 18 hours

Answer: c. 131hours
5

Explanation:
Tank filled or work done by P in 1 hour = 1
22
Tank filled or work done by Q in 1 hour (Q takes 11 hrs more than P) =1
33
Tank filled or work done by both pipes in 1 hour =1+1=5
223366
So the entire tank is full in66= 131hours
55

Tip:
If A completes1amount of work in 1 day, he completes entire work in 'n' days.
n


2. Pipe A takes 38 hours to fill a tank alone while Pipe B takes half the time taken by Pipe A to fill the same tank alone. The leakage C can empty the entire tank in 133 hours. How many hours will it take to fill the tank if Pipe A and B are opened together and leakage C is also allowed to empty the tank simultaneously?

a. 14 hours
b. 19 hours
c. 28 hours
d. 95 hours

Answer: a. 14 hours

Explanation:

Tank filled by A in 1 hour =1
38
Tank filled by B in 1 hour (A takes 38 hrs, so B would take 19 hrs) =1
19
Tank emptied by leakage C in 1 hour =1
133
Tank filled by all 3 openings together in 1 hour =1+1-1
3819133
Making denominators common,
Tank filled by all 3 pipes together in 1 hour =3.5+7-1=9.5=1
13313313313314
So the entire tank is full in14= 14 hours -------------> Inverse or reciprocal of1
114


3. Pipe A can fill a tank in 22.5 minutes while a diametrically bigger Pipe B can do it in 15 minutes. Initially we open both the pipes together for some time but after how much time, should we close Pipe B so that the tank is full in 18 minutes?

a. 2.5 minutes
b. 3 minutes
c. 4 minutes
d. 4.5 minutes

Answer: b. 3 minutes

Explanation:

A fills tank in 22.5 minutes and A remains open for 18 minutes ------------ Given

So total tank filled by A = Tank filled in 1 min x 18 minutes =1x 18 =4
22.55
This is the entire work done by A.
So whatever is the remaining work, it is done by only B
Let B be open for T minutes.
Total tank filled by B = 1 -4=1= Tank filled in 1 min x T minutes =1x T
5515
1=1x T
515
∴ T = 3 minutes = B should be closed after this much time


4. Pipe P can fill a cement tank in 24 hours. However, there is a leakage at the bottom of the tank due to which the Pipe P takes 12 hrs longer and fills it in 36 hours. How long would this leakage take to empty the entire tank?

a. 48 hours
b. 60 hours
c. 72 hours
d. 96 hours

Answer: c. 72 hours

Explanation:

Normally, Pipe P can fill the cement tank in 24 hours. So in 1 hour it fills =1part of tank
24
Due to leak, Pipe P can fill the tank in 36 hours. So in 1 hour it actually fills =1part of tub
36
∴ Water removed by the leak in 1 hour =1-1=1
243672
∴ Leak empties the tank in 72 hours.


5. Tap B is 5 times slower than Tap A in filling the same tank. Also tap B takes 32 minutes more than Tap A to fill the same tank completely. How long will the tank take to get full, if both the taps are opened simultaneously?

a.5minutes
32
b.32minutes
5
c.20minutes
3
d.32minutes
3

Answer: c.20minutes
3

Explanation:

Let Tap A take T minutes to fill the tank alone.
Since Tap A is 5 times faster than Tap B, Tap B takes 5 times more time.
So time taken by Tap B = 5T minutes
Also, 5T-T = 32 ------------------- Given
∴ T = 8 minutes = Time taken by A
Time taken by B = 5 x 8 = 40 minutes.
In 1 min, A + B fills =1+1=3part of tank
84020
So entire tank is filled in20minutes -------------> Inverse or reciprocal of3
320