Question

A pipe can fill a tank in 12 minutes and another pipe can fill it in 15 minutes, but a third pipe can empty it in 6 minutes. The first two pipes are kept open for 5 min in the beginning and then third pipe is also opened. Time taken to empty the water tank is

Answer 1

Answer: 45 min

In 1 min

1st pipe fills =1/12

2nd pipe fills =1/15

In 1st 5 min

fraction of tank filled = 5/12 + 5/15

=(25+20)/60

=45/60

=3/4

Since the 3 pipes are opened after 5 mins,

fraction emptied in 1 min = 1/6 - (1/12 + 1/15)

=(10-5+4)/60

=1/60

===>60 min to empty fully filled tank

Since the tank is 3/4 filled

Time taken to empty = 60*3/4

=45 minutes.

Hope it helped :)

If it helped please mark as brainliest....

Answer 2

Answer:

45 minutes

Explanation:

12 5

15 60 4

-6 -10

Pipe filled by A & B in 5 minutes

(5+4)×5 = 45

Then let. x be time taken to empt.

(5+4-10) x = 45

x = - 45 minutes