2.2000 u/ml or 2000 u/0. 1 ml.
3.2 thousand units/ml or 200 units /0. 1 ml
4.500 units/ml or 50u/0. 1 ml.
The formula used in the fourth question is wrong, it should be:
Infusion coefficient = infusion time × infusion drops per minute × infusion volume.
10×50×60÷ 1000=30