Hello Aspirants. Welcome to Online Quantitative Aptitude Section with explanation in AffairsCloud.com. Here we are creating question sample in **Pipes & Cistern **which is common for all competitive exams. We have included Some questions that are repeatedly asked in bank exams !!!

**A Special pump can be used for filling as well as for emptying a Cistern. The capacity of the Cistern is 2400m³. The emptying capacity of the Cistern is 10m³ per minute higher than its filling capacity and the pump needs 8 minutes lesser to Cistern the tank than it needs to fill it. What is the filling capacity of the pump?**

A. 40m³/min

B. 50m³/min

C. 60m³/min

D. 30m³/min

E. None of the Above

Answer –**B. 50m³/min**

**Explanation :**

Filling Capacity of the Pump = x m/min

Emptying Capacity of the pump = (x+10) m/min

2400/x – 2400/x+10 = 8

(x – 50) + (x + 60) = 0

x = 50**Three pipes P, Q and R can fill a Cistern in 6 hours. After working at it together for 2 hours, R is closed and P and Q can fill the remaining part in 7 hours. The number of hours taken by R alone to fill the Cistern is**

A. 14 hours

B. 12 hours

C. 15 hours

D. 18 hours

E. None of the Above

Answer –**A. 14 hours**

**Explanation :**

Part filled in 2 hours = 2/6 = 1/3

Remaining Part = (1-1/3) = 2/3

(P + Q)’s 7 hour work = 2/3

(P + Q)’s 1 hour work = 2/21

R’s 1 hour work = (P + Q + R) 1 hour work – (P + Q) 1 hour work

= (1/6 – 2/21) = 1/14 = 14 hours**A Cistern is two-fifth full. Pipe A can fill a tank in 10 minutes and 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. 5 minutes

B. 4 minutes

C. 6 minutes

D. 8 minutes

E. None of the Above

Answer – C. 6 minutes

**Explanation :**

pipe B is faster than pipe A and so,the tank will be emptied.

part to be emptied = 2/5

part emptied by (A+B) in 1 minute= (1/6 – 1/10) = 1/15

1/15 : 2/5 :: 1: x

2/5 * 15 = 6 minutes.**If a pipe A can fill a tank 3 times faster than pipe B. If both the pipes can fill the tank in 32 minutes, then the slower pipe alone will be able to fill the tank in?**

A. 128 minutes

B. 124 minutes

C. 154 minutes

D. 168 minutes

E. None of the Above

Answer –**A. 128 minutes**

**Explanation :**

Time is taken by pipe A = x

Time is taken by pipe B = x/3

1/x + 3/x = 1/32

x = 128 minutes**A large cistern can be filled by two pipes P and Q in 15 minutes and 20 minutes respectively. How many minutes will it take to fill the Cistern from an empty state if Q is used for half the time and P and Q fill it together for the other half?**

A. 12 minutes

B. 17 minutes

C. 18 minutes

D. 19 minutes

E. None of the Above

Answer –**A. 12 minutes**

**Explanation :**

Part filled by P and Q = 1/15 + 1/20 = 7/60

Part filled by Q = 1/20

x/2(7/60 + 1/20) = 12 minutes**A pipe can fill a cistern in 16 hours. After half the tank is filled, three more similar taps are opened. What is the total time taken to fill the cistern completely?**

A. 3 hours

B. 2 hours

C. 9 hours

D. 4 hours

E. None of the Above

Answer –**C. 9 hours**

**Explanation :**

In One hour pipe can fill = 1/16

Time is taken to fill half of the tank = 1/2 * 16 = 8 hours

Part filled by four pipes in one hour = (8*1/16) = 1/2

Required Remaining Part = 1/2

Total time = 8 + 1 = 9**Two pipes P and Q are opened together to fill a tank. Both the pipes fill the tank in time “x” If Q separately took 25 minutes more time than “x” to fill the tank and Q took 49 minutes more time than “x” to fill the tank, then find out the value of x?**

A. 48 minutes

B. 35 minutes

C. 54 minutes

D. 68 minutes

E. None of the Above

Answer –**B. 35 minutes**

**Explanation :**

Time is taken to fill the tank by both Pipes x = √a*b

x = √25*49 = 5 * 7 = 35**Three taps P, Q and R can fill a tank in 12, 15 and 20 hours respectively. If P is open all the time and Q, R are open for one hour each alternatively, the tank will be full in**

A. 3 hours

B. 2 hours

C. 7 hours

D. 4 hours

E. None of the Above

Answer –**C. 7 hours**

**Explanation :**

(P + Q)’s 1 hour work = 1/12 + 1/15 = 3/20

(P + R)’s 1 hour work = 1/12 + 1/20 = 2/15

For 2 hrs = (3/20 + 2/15) = 17/60

For 6 hrs = (3*17/60) = 17/20

Remaining Part = 1 – 17/20 = 3/20 filled by P and Q in 1 hour**Pipe A fills a tank in 30 minutes. Pipe B can fill the same tank 5 times as fast as pipe A. If both the pipes were kept open when the tank is empty, how much time will it take for the tank to overflow?**

A. 3 minutes

B. 2 minutes

C. 5 minutes

D. 4 minutes

E. None of the Above

Answer –**C. 5 minutes**

**Explanation :**

Total Capacity = 90L.

Tank filled in 1 minute by A = 3L

Tank filled in 1 minute by B = 15L

The capacity of the tank filled with both A and B in 1 minute = 18L.

overflow = 90/18 = 5 minutes.**Two pipes P and Q can fill a cistern in 10 hours and 20 hours respectively. If they are opened simultaneously. Sometimes later, tap Q was closed, then it takes total 5 hours to fill up the whole tank. After how many hours Q was closed?**

A. 14 hours

B. 15 hours

C. 10 hours

D. 16 hours

E. None of the Above

Answer –**C. 10 hours**

**Explanation :**

Pipe P Efficiency = 100/10 = 10%

Pipe Q Efficiency = 100/20 = 5%

Net Efficiency = 15%

15x + 10(5-x) = 100

x = 10

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