Pipes and Cistern- Aptitude Questions and Answers

View in English View in Hindi

Three pipes A, B and C together can fill a cistern in 6 hours. After working together for 2 hours, C is closed and A and B fill the remaining cistern in 8 hours. Then the time in which the cistern can be filled by pipe C alone will be:

A)
11 hours

B)
9 hours

C)
12 hours

D)
10 hours


Correct Answer :

12 hours


Explanation :

Three Pipes A,B and C together filled a tank in 6 hours
So 1 hour work of A,B and C =1/6
C closed after 2 hour's, Part filled in 2 hours working together(A,B and C) = 2/6 = 1/3
Remaining part = (1-1/3) = 2/3

A and B can fill remaining in 8 hours, (A + B)'s 8 hour's work = 2/3

So, (A+B)'s 1 hour work = 2/24=1/12

Therefore C's 1 hour's work
= [(A+B+C)'s 1 hour]-[(A+B)'s 1 hr work]
=(1/6 - 1/12) = 1/12

C alone can fill the tank in 12 hours

Two pipes A and B can fill a cistern in 4 and 6 minutes respectively. If both the pipes kept turned on alternatively for one minute each starting from A, how long will it take to fill the cistern?

A)
3(3/7) minutes

B)
6 minutes

C)
4(2/3) minutes

D)
6(6/7) minutes


Correct Answer :

4(2/3) minutes


Explanation :

As the pipes are operating alternatively for one minute, thus (A+B)'s 2 minutes job is =(1/4 +1/6) =5/12
in next, 2 minutes both pipe can fill another 5/12 part.
So in 4 minutes A and B are operating alternatively will fill 5/12 + 5/12 = 5/6

Remaining part of cistern= 1 - 5/6 =1/6

Pipe A can fill 1/4 part of the cistern in 1 minute,and can fill 1/6 part of the cistern in = 4*(1/6) =2/3 minutes

Total time taken to fill the Cistern = time taken to fill (5/6 part + 1/6 part)
=> 4 minutes + 2/3 minutes = 4(2/3) minutes Or, 4 minutes 40 seconds

Pipe A can fill a tank in 45 hrs and pipe B can fill it in 36 hrs. If both the pipes are opened in the empty tank. In how many hours will it be full?

A)
10 hr

B)
15 hr

C)
20 hr

D)
28 hr


Correct Answer :

20 hr


Explanation :

If a pipe can fill a tank in x hours, then : part filled in 1 hour = 1/x

Part filled A in 1 hr= (1/45)
Part filled B in 1 hr= (1/36)
Part filled by (A+B) together in 1 hr=(1/45)+(1/36)=1/20

So, The tank will be full in 20 hr.

If a pipe fills a tank in 6 h, then what part of the tank will the pipe fill in 1 h?

A)
1/3

B)
1/6

C)
1/4

D)
1/5


Correct Answer :

1/6


Explanation :

If a pipe can fill a tank in x hours, then : part filled in 1 hour = 1/x

Then,when a pipe fills a tank in 6 h, then the part of tank filled in 1 h = 1/6
Hence ,required part of the tank to be filled in 1h = 1/6 part

A tap can fill a tank in 16 minutes and another can empty it in 8 minutes. If the tank is already half full and both the taps are opened together, the tank will be ?

A)
Filled in 12 min

B)
Emptied in 12 min

C)
Filled in 8 min

D)
Emptied in 8 min


Correct Answer :

Emptied in 8 min.


Explanation :

If a pipe can fill a tank in x hours and another pipe can empty the full tank in y hours (where x > y), then on opening both the pipes, the net part emptied in 1 hour = (1/y)-(1/x)

= (1/8 - 1/16) = 1/16
Time taken to empty the full tank = 16 min.
Hence, time taken to empty the half tank = 8 min

One tap can fill a cistern in 2 hours and another can empty the cistern in 3 hours. How long will they take to fill the cistern if both the taps are opened ?

A)
5 hours

B)
6 hours

C)
7 hours

D)
8 hours


Correct Answer :

6 hours


Explanation :

If a pipe can .fill a tank in x hours and another pipe can empty the full tank in y hours (where y> x), then on opening both the pipes, the net part filled in 1 hour = (1/x)-(1/y)

= (1/2 - 1/3) = 1/6
Hence, time taken to fill the cistern = 6 hours

Latest Updates

General Knowledge of MP

Under the Madhya Pradesh Ladli Laxmi Yojana, the beneficiary is paid the total amount on attaining the age of ?

Indian Politics

Who appoints the Chairman and the Members of the Union Public Service Commission?

General Knowledge of World

Which country will host the 2022 Football World Cup?

Area

The angles of a triangle are in the ratio 2 : 4 : 3. The smallest angle of the triangle is?

Which one of the following triples does not represent the sides of a triangle?

If the perimeter of a rectangle is 10 cm and the area is 4 cm2, then its length is?

Height and Distance

An aeroplane flying at a height of 300 m above the ground passes vertically above another plane at an instant when the angles of elevation of the two planes from the same point on the ground are 60º and 45º respectively. What is the height of the lower plane from the ground?

From the top of a building 90 m high, the angles of depression of the top and the bottom of a tree are 30º and 45º respectively. What is the height of the tree?

Trigonometry

What is the value of sinx √( 1 /1+cosx + 1 /1-cosx ) ?

What is cos4 A - sin4 A / cos2 A - sin2 A equal to?

If 7sin2 x +3cos2 x = 4, 0 < x < 90º ,then what is the value of tan x?

If x = a cosθ + b sinθ and y = a sinθ - b cosθ then what is x2 + y2 equal to?

Average

The mean of 5 numbers is 15. If one more number is included, the mean of the 6 numbers becomes 17. What is the included number?

The mean marks obtained by 300 students in a subject are 60. The mean of top 100 students was found to be 80 and the mean of last 100 students was found to be 50. The mean marks of the remaining 100 students are?

In an asymmetrical distribution, of the mean and median of the distribution are 270 and 220 respectively, then the mode of the data is?

Let a, b, c, d, e, f, g be consecutive even numbers and j, k, l, m, n be consecutive odd numbers. What is the average of all the numbers?

Alligation or Mixture

25 kg of alloy X is mixed with 125 kg of alloy Y. If the amount of lead and tin in the alloy X is the ratio 1 : 2 and the amount of lead and tin in the alloy Y is in the ratio 2 : 3, then what is the ratio of lead to tin in the mixture?

Simplification

The ratio of two numbers is 1 : 5 and their product is 320. What is the difference between the square of these two numbers?