Question

There are 3 pipes in our tank with these 3 pipes separately the tank can be filled up in 18,21 and 24 hours respectively. (a) If all the 3 pipes remain open together let's make proportion and calculate when the tank will be filled with water. (b) If the first two pipes would remain open, let's calculate the time to fill up the tank with water. (c) If the last two pipes would remain open, let's calculate the time to fill up the tank. ​

Answer 1

Answer:

if the last two pipes would remain open let's calculate the time to fill up the tank

Answer 2

Part of the tank emptied in 1 hour = 1 - (

3

1

+

15

4

)=1−

15

9

=

15

6

=

5

2

(∵3hrs45min=3

60

45

=

4

15

hrs)

Time taken to empty the full tank =

5

2

1

=

2

5

hrs

∴ Time taken to empty the exactly half filled tank =

2

1

×

2

5

hours=

4

5

hours=1hr15min