Question

a drug is supplied as a 20 mg/ml solution in a 50 ml vial. you need to make 15 ml of a 10 mg/ml solution. how much concentrate and how much diluent are needed to obtain the desired final volume?

Answer 1

you need x ml of solution, and 15-x ml of water (0 mg/ml), so

20x + 0 = 10*15
x = 7.5

Since the concentration is being reduced by a factor of 2, the volume needs to be increased by that factor.

2 * 7.5 = 15