How many milligrams are in 0.5 mL of this solution?

How many milligrams are in 0.5 mL of this solution?

• A. 3 mg
• B. 15 mg
• C. 7.5 mg
• D. 1.5 mg

Answer: (C)

Understanding how to convert a volume of a solution to the amount of drug it contains relies on the concentration, expressed as mg per mL. If the solution has a concentration of 15 mg/mL, then the amount in 0.5 mL is found by multiplying: 0.5 mL × 15 mg/mL = 7.5 mg. So the correct amount is 7.5 mg. If you check the other possibilities, they would come from different volumes at the same concentration (for example, 3 mg would be in 0.2 mL, 1.5 mg in 0.1 mL, and 15 mg in 1 mL), which shows why 0.5 mL corresponds to 7.5 mg.

Understanding how to convert a volume of a solution to the amount of drug it contains relies on the concentration, expressed as mg per mL. If the solution has a concentration of 15 mg/mL, then the amount in 0.5 mL is found by multiplying: 0.5 mL × 15 mg/mL = 7.5 mg. So the correct amount is 7.5 mg.

If you check the other possibilities, they would come from different volumes at the same concentration (for example, 3 mg would be in 0.2 mL, 1.5 mg in 0.1 mL, and 15 mg in 1 mL), which shows why 0.5 mL corresponds to 7.5 mg.