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 !!!

**Three pipes A, B and C can fill a cistern in 6 hours. After working at it together for 2 hours, C is closed and A and B can fill the remaining part in 6 hours. The number of hours taken by C alone to fill the cistern is**

A.12hrs

B.10hrs

C.18hrs

D.8hrs

E.None of these

Answer –**C.18hrs**

**Explanation :**

A+B+C in 1h = 1/6

A+B+C in 2h = 2/6 = 1/3

Remaining = 1-1/3 = 2/3

A+B in 6hrs = 2/3

A+B in 1hr = 2/18

C alone to fill the cistern = 1/6 – 2/18 = 3-2/18 = 1/18

**Pipes A and B can fill a tank in 5 and 3 hrs respectively. Pipe C can empty empty it in 15 h. The tank is half full. All the three pipes are in operation simultaneously. After how much time the tank will be full ?**

A.1(7/15)hrs

B.2(1/11)hrs

C.1(1/14)hrs

D.2(3/11)hrs

E.None of these

Answer –**C.1(1/14)hrs**

**Explanation :**

In 1 hr = 1/5+1/3 – 1/15 = 3+5-1/15 = 7/15

½ tank filled by 3 pipes = 15/7*1/2 = 15/14 =1(1/14)

**Two pipes A and B can fill a tank in 10 minutes and 20 minutes respectively. Both the pipes are opened together but after 4 minutes, Pipe A is turned off. What is the total time required to fill the tank ?**

A.12m

B.10m

C.8m

D.16m

E.None of these

Answer –**A.12m****Explanation :**

A + B in 4 minute = 4 ( 1 / 10 + 1 / 20 ) = 4(2+1/20) = 12/20 = 3/5

Part remaning = 1 – ( 3 / 5 ) = 2 / 5

1 / 20 part is filled by B in 1 minute

2 / 5 part will be filled in = ( 20)* ( 2 / 5 ) = 8 minutes

Total = 8+4 = 12m

**Two pipes A and B can fill a tank in 6 hours and 5 hours respectively. If they are turned on alternatively for 1 hour each, find the time in which the tank is full. (Assume pipe A is opened first)**

A.4hrs 30min

B.5hrs

C.6hrs 25min

D.5hrs 30min

E.None of these

Answer –**D. 5hrs 30min**

**Explanation :**

Total= 30, A = 30/6 =1/5, B = 30/5 =1/6

In 2 hrs = 5+6 =11

In 4hrs = 22

Remaining = 30-22 =8

1hr Pipe A = 8-5= 3,Remaining B = 3*1/6 = 30min

Total = 5hrs 30min

**Pipes A, B and C can fill a tank in 3, 4 and 6 hours respectively. If all the pipes are opened together and after 30 minutes pipes B and C are turned off, find the total time in which the tank is full.**

A.2(3/8)hrs

B.1(1/7)hrs

C.2(2/7)hrs

D.3(1/3)hrs

E.None of these

Answer –**A.2(3/8)hrs**

**Explanation :**

In 1 hr A, B, C = 1/3+1/4+1/6 = 8+6+4/24 = 18/24 = 6/8 = ¾

Filled in 30m = 3/8

Remaining = 1-3/8 =5/8

Pipe A = 3*5/8 = 15/8

Total = 15/8+1/2 = 15+4/8 = 19/8 = 2(3/8) hrs

**Two pipes M and N can fill a tank in 30 and 45 minutes respectively. If both the pipes were open for few minutes after N was closed and the tank was full in 25 minutes, find the time for pipe N was open.**

A.8.16m

B.7.5min

C.5min

D.10.2m

E.None of these

Answer –**B.7.5min**

**Explanation :**

X(1/30+1/45) + 1/30(25-x) = 1

x/45+25/30 =1

x/45 = 5/30 =1/6

x=45/6

x=7.5m

**A cistern is filled by 3 pipes A, B and C with uniform flow. The second pipe B takes3/2 times the time taken by A to fill the tank, while C takes twice the time taken by B to fill the tank. If all the three pipes can fill the tank in 7 hours, find the time required by pipe A alone to fill the tank.**

A.10hrs

B.12hrs

C.14hrs

D.15hrs

E.None of these

Answer –**C.14hrs**

**Explanation :**

1/x + 1/ (3/2x) + ½(3x/2) = 1/7

6/3x = 1/7

3x/6 = 7

3x=42

X=14

**Two pipes P and Q can fill a tank in 8 hours. If only pipe P is open then it would take 4 hours longer to fill the tank. Find how much longer would it take if only pipe Q is open.**

A.16hrs

B.12hrs

C.10hrs

D.8hrs

E.None of these

Answer –**A.16hrs**

**Explanation :**

P= 8+4 = 12

P+Q= 1/8

Q= 1/8 – 1/12 = 3-2/24 = 1/24

Q= 24

Q alone= 24-8 = 16

**Two pipes P and Q can fill a tank in 20m and 30m respectively. If both the pipes are opened simultaneously, after how much time should Q be closed so that the tank is full in 16minutes ?**

A.12min

B.6min

C.10min

D.7min

E.None of these

Answer –**B.6min**

**Explanation :**

X(1/20+1/30) +(16-x)1/20 = 1

5x/60+16-x/20 =1

5x+48-3x/60 =1

2x+48 = 60

2x=12

X=12/2 = 6

**A tap can fill a tank in 12 minutes and another tap can empty the tank in 6 minutes.If the tank is already full and then both the taps are opened the tank will be**

A.Filled in 6 minutes

B.Emptied in 6 minutes

C.Filled in 6 minutes

D.Emptied in 12 minutes

E.None of these

Answer –**D.Emptied in 12 minutes**

**Explanation :**

1/12 – 1/6 = 1-2/12 = -1/12

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