The height of a door knob above the floor is approximately?

yes this is an actual question from my physics review. a step by step on how the answer is found would be for full understanding. you.

There is a standard (you would not believe) that knobs are on the level of 1m 

i would say that in order to apply less force to open a door you need to position knob in the middle of the door. 

door itself would be probably about 2m (average person is 1.8m)

so it's half of 2m -> 1m

Look it up you feel me