Answer:
600 ml of pure water.
Step-by-step explanation:
To determine how much pure water the pharmacist should add to a 600ml solution with 30% active ingredient, so that this solution becomes 15%, the following calculation must be performed:
600 x 0.3 = 180
15 = 180
100 = X
100 x 180/15 = X
18,000 / 15 = X
1,200 = X
1,200 - 600 = 600
Thus, 600 ml of pure water should be added to achieve a 15% solution.
