A client is to receive 1 mg of a medication. If the medication is available in a solution of 5 mg/9 mL, how many mL of the medication should the client receive?

• A. 0.2
• B. 0.6
• C. 1.4
• D. 1.8

Answer: (D)

This question tests how to convert a prescribed milligram dose into the volume of a solution using the solution’s concentration. With 5 mg in 9 mL, the concentration is 5 mg/9 mL. To get 1 mg, multiply by the ratio that scales the dose: 1 mg × (9 mL / 5 mg) = 9/5 mL = 1.8 mL. A quick check confirms the math: 1.8 mL × (5 mg/9 mL) = 1 mg. Therefore, the patient should receive 1.8 mL.