What derived unit is appropriate for expressing rate of water flow, speed and volume of a room?

In this question there are three physical quantities which are named as rate of water flow ,speed and volume of a room.

we are asked to determine the derived unit of these physical quantities .

The volume of a room  is given as-

                                   volume = length ×breadth×height

                                        ⇒ V= l×b×h

Here l=length,b= breadth,h = height

In S.I system the unit of  distance is metre[ m].

Hence the derived unit of volume is = metre×metre×metre

                                                            = cubic metre

The speed of a body is defined as the distance  travelled by the body in unit time.

Mathematically speed is written as -

In S.I unit ,the unit of time is second .Hence the derive unit of speed is -

The rate of water flow is defined as volume of water flown per unit time.

Mathematically it is written as -

                                           where V is the volume and V' is the rate of flow of water]

The derive unit of rate of flow of water is calculated as -