A solution with a concentration of 0.25 mg/mL is used to deliver a 2 mg dose. How many milliliters are required?

A solution with a concentration of 0.25 mg/mL is used to deliver a 2 mg dose. How many milliliters are required?

• A. 4 mL
• B. 6 mL
• C. 8 mL
• D. 10 mL

Answer: (C)

To determine the volume, divide the required dose by the concentration. The dose is 2 mg and the concentration is 0.25 mg/mL, so volume = 2 mg ÷ 0.25 mg/mL = 8 mL. This works because 8 mL × 0.25 mg/mL = 2 mg. For quick checks: 4 mL would give 1 mg, 6 mL would give 1.5 mg, and 10 mL would give 2.5 mg, so only 8 mL delivers the exact 2 mg.

To determine the volume, divide the required dose by the concentration. The dose is 2 mg and the concentration is 0.25 mg/mL, so volume = 2 mg ÷ 0.25 mg/mL = 8 mL. This works because 8 mL × 0.25 mg/mL = 2 mg. For quick checks: 4 mL would give 1 mg, 6 mL would give 1.5 mg, and 10 mL would give 2.5 mg, so only 8 mL delivers the exact 2 mg.