Question

A pipe can empty a tank in 40 minutes. A second pipe with diameter twice as much as that of the first is also attached with the tank to empty it. The two pipe together can empty it. The two pipe together can empty the tank in.

Answer 1

Answer:

Read Solution (Total 2)

8 minutes

If first pipe that can empty a tank in 40 minutes has radius 'r', its 1 min. empty rate=1/40

As the second pipe has double the diameter than first will have radius=2r, so its flow will be directly proportional to cross sectional area=Pi*(2r)^2=4*Pi*r^2, which is 4 times the first pipe.

So the empty rate of second pipe=4/40=1/10

So together both pipes can empty the tank in 1/[(1/40)+(1/10)]=8 min.

***21/20+1/40=3/40

so it will be emptied in 40/3 min.

Answer 2

Answer:

Step-by-step explanation: