Pipes and Cistern - Quantitative Aptitude (MCQ) questions

1)   A cistern has two taps attached to it. Tap B can empty the cistern in 45 minutes. But Tap A can fill the cistern in just 30 minutes. Rohit started both taps unknowingly but realized his mistake after 30 minutes. He immediately closed Tap B. Now after this, in how much time will the cistern be filled?
- Published on 03 May 17

a. 30 minutes
b. 45 minutes
c. 15 minutes
d. 20 minutes
Answer  Explanation 

ANSWER: 20 minutes

Explanation:
pipes and cisterns


2)   Pipe R can empty a full tank in 30 hours. But two pipes P and Q can fill a tank in 15 hours and 10 hours respectively. Ram unknowingly opened all three taps. After 2 hours Shyam realized it and closed Pipe R. Due to this mistake how much time more would it take to fill the tank?
- Published on 03 May 17

a. 18 minutes
b. 24 minutes
c. 1 hour 20 minutes
d. 2 hours 15 minutes
Answer  Explanation 

ANSWER: 24 minutes

Explanation:
pipes and cisterns


3)   A cistern is filled by Pipe A and Pipe B together in 2.4 hours. Pipe A alone can fill the cistern at the rate of 100 litres per hour. Pipe B alone can fill the cistern in 4 hours. What is the capacity of the cistern?
- Published on 13 Apr 17

a. 1200 litres
b. 600 litres
c. 1000 litres
d. 500 litres
Answer  Explanation 

ANSWER: 600 litres

Explanation:
pipes and cisterns


4)   There is a leak at the bottom of a cistern. Due to this it takes 8 hours to fill the cistern. Had there not been a leak, it would take one hour less to fill the cistern. How much time does it take for the leak to completely empty the cistern?
- Published on 12 Apr 17

a. 48 hours
b. 55(1/3) hours
c. 56 hours
d. 15 hours
Answer  Explanation 

ANSWER: 56 hours

Explanation:
pipes and cisterns


5)   Tap P alone fills a cistern in 2 hours; while tap Q alone fills the same cistern in 3 hours. A new tap R is attached to the bottom of the cistern which can empty the completely filled cistern in 6 hours. Sunny started all three taps together at 9am. When will the tank be full?
- Published on 11 Apr 17

a. 10.30 am
b. 11.15 am
c. 12 pm
d. 9.45 am
Answer  Explanation 

ANSWER: 10.30 am

Explanation:
pipes and cisterns


6)   A cistern can be filled in 6 hours by taps P and Q. If tap R also joins them, then cistern is filled in 5 hours. Tap P can fill the cistern at twice the rate of tap Q. In what time tap Q and R fill the cistern?
- Published on 11 Apr 17

a. 9.75 hours
b. 10. 90 hours
c. 11.25 hours
d. 12.90 hours
Answer  Explanation 

ANSWER: 11.25 hours

Explanation:
pipes and cisterns


7)   A cistern is normally filled with water in 10 hours but takes 5 hours longer to fill because of a leak in its bottom. If the cistern is full, the leak will empty the cistern in
- Published on 11 Apr 17

a. 20 hours
b. 40 hours
c. 50 hours
d. 30 hours
Answer  Explanation 

ANSWER: 30 hours

Explanation:
pipes and cisterns


8)   A tank has three taps P, Q and R. Taps P and Q can fill the tank in 1.5 and 2 hours, respectively. Tap R can empty the completely filled tank in just half hour. Tap P is opened at 8 am, tap Q is opened at 9am and tap R is opened at 10 am. At what exact time will the tank be empty?
- Published on 17 Mar 17

a. 12 pm
b. 1.25 pm
c. 12.12 pm
d. 12.28 pm
Answer  Explanation 

ANSWER: 12.12 pm

Explanation:
pipes and cisterns


9)   A pipe can fill a tank in 6 hours. Another pipe can empty the tank in 12 hours. If both pipes are opened simultaneously, the part of tank filled by both pipes in 1 hour is?
- Published on 17 Mar 17

a. 1/9 th part
b. 1/6 th part
c. 1/12 th part
d. 1/3 rd part
Answer  Explanation 

ANSWER: 1/12 th part

Explanation:
pipes and cisterns


10)   A tap having diameter 'd' can empty a tank in 84 min. How long another tap having diameter '2d' take to empty the same tank?
- Published on 15 Mar 17

a. 21 minutes
b. 42 minutes
c. 168 minutes
d. 28 minutes
Answer  Explanation 

ANSWER: 21 minutes

Explanation:
pipes and cisterns


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