How many milliliters of sterile water for injection should be added to a vial containing 5 mg/mL of a drug to prepare a solution containing 1.5 mg/mL of the drug

7mL of sterile water is the initial amount of the concentrated solution is 3mL

Explanation:

In this problem, the vial must be diluted from 5mg/mL to 1.5mg/mL, that means the solution must be diluted:

5mg/mL / 1.5mg/mL = 3.33 times

If the initial amount of the drug in the vial is 3mL, the final volume must be:

10mL

That means the volume of water that should be added is:

10mL - 3mL: