This set of Aptitude Questions and Answers (MCQs) focuses on “Two Pipes”.

1. 2 pipes can fill a tank in 4 minutes and 9 minutes, respectively. How long will it take to fill the tank if both the pipes are opened simultaneously?

a) 1.22 minutes

b) 1.5 minutes

c) 2.2 minutes

d) 2.76 minutes

View Answer

Explanation: Let the capacity of the tank be 36 liters.

The efficiency of the pipes = 9, 4 respectively.

The relative efficiency = 9 + 4 = 13

The time taken = 36 / 13 = 2.76 minutes

2. 2 pipes can fill a tank in 11 minutes and 13 minutes, respectively. Find the time taken to fill the tank if both the pipes are opened simultaneously.

a) 5 minutes

b) 12 minutes

c) 6 minutes

d) 8 minutes

View Answer

Explanation: Let the capacity of the tank be 143 liters.

The efficiency of the pipes = 13, 11 respectively.

The time taken = 143 / 24 = 5.95 minutes ≈ 6 minutes

3. 2 pipes can fill a tank in 28x and 12x minutes, respectively. Find the ratio of their efficiency.

a) 7 : 8

b) 7 : 3

c) 8 : 7

d) 3 : 7

View Answer

Explanation: The ratio of efficiency is inverse of the ratio of time.

The ratio of time = 28 : 12 = 7 : 3

The ratio of efficiency = 3 : 7

4. Two pipes can fill a tank in 143 minutes and 187 minutes, respectively. Find the ratio of their efficiency.

a) 12 : 17

b) 17 : 12

c) 13 : 17

d) 17 : 13

View Answer

Explanation: The ratio of efficiency is inverse of the ratio of time.

The ratio of time = 143 : 187 = 13 : 17

The ratio of efficiency = 17 : 13

5. 2 pipes can fill a tank in 12 minutes when opened together. If first pipe can fill the tank in 16 minutes, find the time taken by the second pipe to fill the tank.

a) 24 minutes

b) 36 minutes

c) 48 minutes

d) 60 minutes

View Answer

Explanation: Let the capacity of the tank be 48 liters.

The efficiency of the pipes combined = 48 / 12 = 4

The efficiency of the first pipe = 48 / 16 = 3

The efficiency of the second pipe = 4 – 3 = 1

The time taken by the second pipe to fill the tank = 48 / 1 = 48 minutes

6. 2 pipes can empty a semi filled tank in 12 minutes and 48 minutes, respectively. How long will it take to empty the entire tank if both the pipes are opened simultaneously?

a) 19.2 minutes

b) 9.6 minutes

c) 19.6 minutes

d) 9.2 minutes

View Answer

Explanation: Let the capacity of the tank be 48 liters.

The efficiency of the pipes = 4, 1

The relative efficiency = 4 + 1 = 5

The time taken = 48 / 5 = 9.6 minutes to empty half the tank.

9.6 * 2 = 19.2 minutes to empty the entire tank.

7. A pipe can fill the tank in 7 minutes and another pipe can empty the tank in 6 minutes. If both the pipes are opened simultaneously, what time will it take to empty the tank?

a) 7 minutes

b) 21 minutes

c) 6 minutes

d) 42 minutes

View Answer

Explanation: Let the capacity of the tank be 42 liters.

The efficiency of the first pipe = 6 and that of the second pipe = 7

The relative efficiency = 1

The required time = 42 / 1 = 42 minutes

8. There are 2 pipes one can fill the tank in 3 minutes and another can empty the tank in 7 minutes. If both the pipes are opened simultaneously, how long will it take to fill quarter of the tank?

a) 1.3125 minutes

b) 1.1325 minutes

c) 1.3215 minutes

d) 1.2315 minutes

View Answer

Explanation: Let the capacity of the tank be 21 liters.

The efficiency of the pipes = 7, 3 respectively.

The relative efficiency = 7 – 3 = 4

The time required to fill quarter of the tank = (21 / 4) / 4 = 1.3125 minutes

9. 2 pipes can fill a tank in 13 minutes and 33 minutes, respectively. Find the time required to fill the tank if both the pipes are opened simultaneously.

a) 9 minutes

b) 9.32 minutes

c) 9.76 minutes

d) 9.89 minutes

View Answer

Explanation: Let the capacity of the tank be 429 liters.

The efficiency of the pipes = 33, 13 respectively.

The relative efficiency = 33 + 13 = 46

The required time = 429 / 46 = 9.32 minutes

10. Two pipes can fill a tank in 120 minutes when opened together. If the efficiency of first pipe is 50% of the second pipe, find the time taken by the second pipe to fill the tank.

a) 2 hours

b) 3 hours

c) 4 hours

d) 5 hours

View Answer

Explanation: Let the capacity of the tank be 120 liters.

Let the efficiency of the second pipe be x.

The efficiency of the first pipe = x / = 0.5x

The relative efficiency = 1.5x = 1

X = 1 / 1.5 = 66.66

The time taken by second pipe to fill the tank = 120 / 66.66 = 120 / 2 * 3 = 180 minutes = 3 hours

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