Quantitative Aptitude

General Questions

Quantitative Aptitude Exercise Mode

General Questions

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Question 1
Two pipes A and B can fill a tank in 20 and 30 minutes respectively. If both the pipes are used together, then how long will it take to fill the tank?

A
12 min
B
15 min
C
25 min
D
50 min
Correct Answer: Option A

Part filled by A in 1 min = 1 .
20

Part filled by B in 1 min = 1 .
30

Part filled by (A + B) in 1 min = 1 + 1 = 1 .
20 30 12

Both pipes can fill the tank in 12 minutes.

Question 2
Pipes A and B can fill a tank in 5 and 6 hours respectively. Pipe C can empty it in 12 hours. If all the three pipes are opened together, then the tank will be filled in:

A
1(13/17) hours
B
2(8/11) hours
C
3(9/17) hours
D
4(1/2) hours
Correct Answer: Option C

Net part filled in 1 hour 1 + 1 - 1 = 17 .
5 6 12 60

The tank will be full in 60 hours i.e., 3 9 hours.
17 17

Question 3
Three pipes A, B and C can fill a tank from empty to full in 30 minutes, 20 minutes, and 10 minutes respectively. When the tank is empty, all the three pipes are opened. A, B and C discharge chemical solutions P,Q and R respectively. What is the proportion of the solution R in the liquid in the tank after 3 minutes?

A
5/11
B
6/11
C
7/11
D
8/11
Correct Answer: Option B

Part filled by (A + B + C) in 3 minutes 

 = 31+1+1=3 x11=11.
3020106020

Part filled by C in 3 minutes =3.
10

Part filled by C in 3 minutes = 3 .
10

Required ratio = 3 x 20 = 6 .
10 11 11

Question 4
A tank is filled by three pipes with uniform flow. The first two pipes operating simultaneously fill the tank in the same time during which the tank is filled by the third pipe alone. The second pipe fills the tank 5 hours faster than the first pipe and 4 hours slower than the third pipe. The time required by the first pipe is:

A
6 hours
B
10 hours
C
15 hours
D
30 hours
Correct Answer: Option C

Suppose, first pipe alone takes x hours to fill the tank .

Then, second and third pipes will take (x -5) and (x - 9) hours respectively to fill the tank.

1 + 1 = 1
x (x - 5) (x - 9)

x - 5 + x = 1
x(x - 5) (x - 9)

(2x - 5)(x - 9) = x(x - 5)

x2 - 18x + 45 = 0

(x - 15)(x - 3) = 0

x = 15.    [neglecting x = 3]

Question 5
One pipe can fill a tank three times as fast as another pipe. If together the two pipes can fill the tank in 36 minutes, then the slower pipe alone will be able to fill the tank in:

A
81 min.
B
108 min.
C
144 min.
D
192 min.
Correct Answer: Option C

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

Then, faster pipe will fill it in x minutes.
3

1 + 3 = 1
x x 36

4 = 1
x 36

x = 144 min.

Question 6
Two pipes can fill a tank in 20 and 24 minutes respectively and a waste pipe can empty 3 gallons per minute. All the three pipes working together can fill the tank in 15 minutes. The capacity of the tank is:

A
60 gallons
B
100 gallons
C
120 gallons
D
180 gallons
Correct Answer: Option C

Work done by the waste pipe in 1 minute 


 =1-1+1
152024


    = 1 - 11
15 120

    = -  1 .    [-ve sign means emptying]
40

Volume of 1 part = 3 gallons.
40

Volume of whole = (3 x 40) gallons = 120 gallons.

Question 7
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
10 min. 20 sec.
B
11 min. 45 sec.
C
12 min. 30 sec.
D
14 min. 40 sec.
Correct Answer: Option D

Part filled in 4 minutes = 4 1 + 1 = 7 .
15 20 15

Remaining part = 1 - 7 = 8 .
15 15

Part filled by B in 1 minute = 1
20

1 : 8 :: 1 : x
20 15

x = 8 x 1 x 20 = 10 2 min = 10 min. 40 sec.
15 3

The tank will be full in (4 min. + 10 min. + 40 sec.) = 14 min. 40 sec.

Question 8
Two pipes A and B can fill a cistern in 37 minutes and 45 minutes respectively. Both pipes are opened. The cistern will be filled in just half an hour, if the B is turned off after:

A
5 min.
B
9 min.
C
10 min.
D
15 min.
Correct Answer: Option B

Let B be turned off after x minutes. Then,

Part filled by (A + B) in x min. + Part filled by A in (30 -x) min. = 1.

x 2 + 1 + (30 - x). 2 = 1
75 45 75

11x + (60 -2x) = 1
225 75

11x + 180 - 6x = 225.

x = 9.

Question 9
A pump can fill a tank with water in 2 hours. Because of a leak, it took 2 hours to fill the tank. The leak can drain all the water of the tank in:

A
4(1/3) hours
B
7 hours
C
8 hours
D
14 hours
Correct Answer: Option D

Work done by the leak in 1 hour = 1 - 3 = 1 .
2 7 14

Leak will empty the tank in 14 hrs.

Question 10
A large tanker can be filled by two pipes A and B in 60 minutes 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
15 min
B
20 min
C
27.5 min
D
30 min
Correct Answer: Option D

Part filled by (A + B) in 1 minute 

 =1+1=1.
604024


Suppose the tank is filled in x minutes.

Then, x 1 + 1 = 1
2 24 40

x x 1 = 1
2 15

x = 30 min.

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