^{3}. The emptying of the tank is 10 m^{3} per minute higher than its filling capacity and the pump needs 8 minutes lesser to empty the tank than it needs to fill it. What is the filling capacity of the pump?

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Two pipes A and B can fill a tank in 15 and 3 minutes respectively. If both the pipes are used together, then how long will it take to fill the tank?

A.

150 sec

B.

15 sec

C.

9 minutes

D.

12 minutes

Answer with explanation

Answer: Option AExplanation

As per given statements,

In 1min, part filled by pipe A = 1/15

In 1min, part filled by pipe B fills = 1/3

Together, in 1min, they fill = (1/15) + (1/3) = 2/5 part

Therefore, together they fill the tank in 5/2min = 150sec

Workspace

One pipe can fill a tank three times as fast as another pipe. If together the two pipes can fill tank in 36 min, then the slower pipe alone will be able to fill the tank in ?

A.

144 min

B.

94 min

C.

187 min

D.

85 min

Answer with explanation

Answer: Option AExplanation

Let the slower pipe alone fill the tank in x min.

Then, faster pipe will fill it in x/3 min.

1/x + 3/x = 1/36

4/x = 1/36 => x = 144 min.

Workspace

Two pipes A and B can fill a tank in 15 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.

14 min. 40 sec.

B.

12 min. 30 sec.

C.

11 min. 45 sec.

D.

10 min. 20 sec.

Answer with explanation

Answer: Option AExplanation

Workspace

Two pipes A and B can fill a tank in 6 hours and 4 hours respectively. If they are opened on alternate hours and if pipe A is opened first, in how many hours, the tank shall be full?

A.

10 hrs

B.

7 hrs

C.

5 hrs

D.

3 hrs

Answer with explanation

Answer: Option CExplanation

Workspace

A cistern is normally filled in 8 hours but takes two hours longer to fill because of a leak in its bottom. If the cistern is full the leak will empty it in.

A.

35 hrs

B.

40 hrs

C.

20 hrs

D.

17 hrs

Answer with explanation

Answer: Option BExplanation

Work done by leak in 1 hour = (1/8 – 1/10) = 1/40

The leak will empty the cistern in 40 hours.

Workspace

Pipe K fills a tank in 30 minutes. Pipe L can fill the same tank 5 times as fast as pipe K. If both the pipes were kept open when the tank is empty, how much time will it take for the tank to overflow?

A.

4 min

B.

3 min

C.

5 min

D.

2 min

Answer with explanation

Answer: Option CExplanation

Let the total capacity of tank be 90 liters.

Capacity of tank filled in 1 minute by K = 3 liters.

Capacity of tank filled in 1 minute by L = 15 liters.

Therefore, capacity of the tank filled by both K and L in 1 minute = 18 liters.

Hence, time taken by both the pipes to overflow the tank = 90/18 = 5 minutes.

Workspace

Pipe A and Pipe B can fill a cistern in 10 hours and 15 hours respectively. When a third pipe C which works as an outlet pipe is also open then the cistern can be filled in 18 hours. The outlet pipe can empty a full cistern in:

A.

14 hours

B.

12 hours

C.

9 hours

D.

8 hours

Answer with explanation

Answer: Option CExplanation

Workspace

Three taps A, B and C can fill a tank in 12, 15 and 20 hours respectively. If A is open all the time and B and C are open for one hour each alternately, the tank will be full in:

A.

B.

7^{1}/_{2} hours

C.

6 hours

D.

7 hours

Answer with explanation

Answer: Option DExplanation

Workspace

Three pipes A, B and C can fill a tank in 6 hours. After working at it together for 2 hours, C is closed and A and B can fill the remaining part in 7 hours. The number of hours taken by C alone to fill the tank is:

A.

14

B.

10

C.

16

D.

12

Answer with explanation

Answer: Option AExplanation

Workspace

^{3}. The emptying of the tank is 10 m^{3} per minute higher than its filling capacity and the pump needs 8 minutes lesser to empty the tank than it needs to fill it. What is the filling capacity of the pump?

A.

60 m^{3} / min.

B.

20 m^{3} / min.

C.

40 m^{3} / min.

D.

50 m^{3} / min.

Answer with explanation

Answer: Option DExplanation

Let the filling capacity of the pump =x m^{3}/min.

Then the emptying capacity of the pump =(x+10) m^{3}/min.

Time required for filling the tank =2400/x minutes.

Time required for emptying the tank =2400/x+10 minutes.

Pump needs 8 minutes lesser to empty the tank than it needs to fill it.

Workspace

A cistern can be filled in 9 hours but it takes 10 hours due to a leak in its bottom. If the cistern is full, then the time that the leak will take to empty it is

A.

90 hr

B.

80 hr

C.

70 hr

D.

60 hr

Answer with explanation

Answer: Option AExplanation

If A can fill a tank in x hours and B can fill a tank in y hours. Then the tank will be filled (empty) in = (xy / y-x) hours

Time taken by A = 9 hours

Time taken by B = 10 hours

Time taken by A and B = (9×10 / 10-9) = 90 hours.

Workspace

A water tank 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.

9 min. to empty

B.

9 min. to full

C.

6 min. to empty

D.

6 min. to full

Answer with explanation

Answer: Option CExplanation

Clearly, 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

x = (2/5 * 1 * 15) = 6 min.

So, the tank will be emptied in 6 min.

Workspace

A large tanker can be filled by two pipes A and B in 60 and 40 minutes respectively. How many minutes will it take to fill the tanker from empty state if B is used for half the time and A and B fill it together for the other half ?

A.

31 min

B.

30 min

C.

35 min

D.

29 min

Answer with explanation

Answer: Option BExplanation

Part filled by (A + B) in 1 minute = (1/60 + 1/40) = 1/24

Suppose the tank is filled in x minutes.

Then, x/2 (1/24 + 1/40) = 1

(x/2) * (1/15) = 1 => x = 30 min.

Workspace

Two pipes can fill a tank in 10 and 14 minutes respectively and a waste pipe can empty 4 gallons per minute. If all the pipes working together can fill the tank in 6 minutes, what is the capacity of the tank?

A.

120 gallons

B.

480 gallons

C.

840 gallons

D.

240 gallons

Answer with explanation

Answer: Option CExplanation

Work done by waste pipe in 1 min = (Part filled by total pipes together) -(part filled by first pipe + part filled by second pipe)

= 1/6 – [(1/10) + (1/14)] = 1/6 – (24/140) = -1/210

Here, negative (-) sign indicates emptying of tank.

To find the capacity, we need to determine the volume of 1/210 part.

Therefore, volume of 1/210 part = 4 gallons ———(given condition)

Hence, the capacity of tank = volume of whole = 4 x 210 = 840 gallons.

Workspace

A water tank can be filled by a tap in 30 minutes and another tap can fill it in 60 minutes. If both the taps are kept open for 5 minutes and then the first tap is closed, how long will it take for the tap to fill the remaining part of the tank?

A.

35 minutes

B.

45 minutes

C.

25 minutes

D.

15 minutes

Answer with explanation

Answer: Option BExplanation

Workspace

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