A 16 cm radius air duct is used to replenish the air of a room 9.0 m x 5.0 m x 4.5 m every 10 min. How fast does the air flow in the duct?

If you looking for flow, I calculated:

20.25 cubic meter/ minute
35.31 cubic feet/minute

If you are looking for velocity, I calculated:

12.43 meter/minute
40.79 feet/minute

If you need these values converted to any other measurement, I suggest onlineconversion.com, you will find every possible conversion there.

Hopefully someone will confirm this answer, it has been a while since I have done calculations like these. Although, I think they are correct.

The air gets into the room through the 16 cm radius air duct. Calculate how long a tube of 16 cm radius should be to hold as much air as the room. Then calculate the speed with which you have to push the air out from that tube with a piston to get all that air in the room in 10 min.