The total mass of insulin in the bottle : m = 4500 mg
Further explanation
Given
225 ml of insulin
The concentration 20 mg/ml
Required
The total mass of insulin
Solution
Density is the ratio of mass per unit volume
Can be formulated
ρ = m / V
m = ρ x V
Input the value :
m = 20 mg/ml x 225 ml
m = 4500 mg