Quantitative Aptitude

General Questions

Quantitative Aptitude Exercise Mode

General Questions

Practice and master this topic with our carefully crafted questions.

5 Questions
8 Minutes
0% Completed
QUEST ? ✓ !
Question 11
A tank is filled in 5 hours by three pipes A, B and C. The pipe C is twice as fast as B and B is twice as fast as A. How much time will pipe A alone take to fill the tank?

A
20 hours
B
25 hours
C
35 hours
D
Cannot be determined
E
None of these
Correct Answer: Option C

Suppose pipe A alone takes x hours to fill the tank.

Then, pipes B and C will take :


xandxhours respectively to fill the tank.
24


1 + 2 + 4 = 1
x x x 5

7 = 1
x 5

x = 35 hrs.

Question 12
A tap can fill a tank in 6 hours. After half the tank is filled, three more similar taps are opened. What is the total time taken to fill the tank completely?

A
3 hrs 15 min
B
3 hrs 45 min
C
4 hrs
D
4 hrs 15 min
Correct Answer: Option B

Part filled by the four taps in 1 hour = 4 x 1 = 2 .
6 3

Remaining part = 1 - 1 = 1 .
2 2

2 : 1 :: 1 : x
3 2

x = 1 x 1 x 3 = 3 hours i.e., 45 mins.
2 2 4

So, total time taken = 3 hrs. 45 mins.

Question 13
Two pipes A and B together can fill a cistern in 4 hours. Had they been opened separately, then B would have taken 6 hours more than A to fill the cistern. How much time will be taken by A to fill the cistern separately?

A
1 hour
B
2 hour
C
6 hour
D
8 hour
Correct Answer: Option C

Let the cistern be filled by pipe A alone in x hours.

Then, pipe B will fill it in (x + 6) hours.

1 + 1 = 1
x (x + 6) 4

x + 6 + x = 1
x(x + 6) 4

x2 - 2x - 24 = 0

(x -6)(x + 4) = 0

x = 6.     [neglecting the negative value of x]

Question 14
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
6 hours
B
6(2/3) hours
C
7 hours
D
7(1/2) hours
Correct Answer: Option C

(A + B)'s 1 hour's work = 1 + 1 = 9 = 3 .
12 15 60 20

(A + C)'s hour's work = 1 + 1 = 8 = 2 .
12 20 60 15

Part filled in 2 hrs = 3 + 2 = 17 .
20 15 60

Part filled in 6 hrs = 3 x 17 = 17 .
60 20

Remaining part = 1 - 17 = 3 .
20 20

Now, it is the turn of A and B 
and3part is filled by A and B in 1 hour.
20


Total time taken to fill the tank = (6 + 1) hrs = 7 hrs.

Question 15
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
10
B
12
C
14
D
16
Correct Answer: Option C

Part filled in 2 hours = 2 = 1
6 3

Remaining part = 1 - 1 = 2 .
3 3

(A + B)'s 7 hour's work = 2
3

(A + B)'s 1 hour's work = 2
21

C's 1 hour's work

   = { (A + B + C)'s 1 hour's work } - { (A + B)'s 1 hour's work }

   = 1 - 2 = 1
6 21 14

C alone can fill the tank in 14 hours.

Previous 1 2
Page 2 of 2