Question
A vial of penicillin solution contains 400,000 U/ml. You are to give 500,000 U. Give:
Answer
The calculated volume is 1.25 mL. Treat this as an educational calculation using the supplied concentration.
Set up the units
The required amount is 500,000 units. Each mL contains 400,000 units, so
Units cancel, leaving mL. The original worksheet uses U and ml; here those are written as units and mL for clarity.
Check by multiplication
The requested amount is 25% greater than the amount in 1 mL, so a volume 25% greater than 1 mL is consistent. This result is exact for the stated numbers; there is no intermediate rounding.
Calculation boundary
This arithmetic does not verify a real medication order. Actual administration also requires verification of the patient, prescription, preparation and concentration, route, allergies, and applicable clinical procedures. The problem supplies no information for those checks. Do not infer a route, frequency, or acceptable patient dose from it.
Evidence boundary
This is MGCCC Level 1 practice question 4, a classroom calculation. The answer uses only the stated dose and concentration; it does not establish that the order, route, formulation, or administration is clinically appropriate. U means units and ml means mL. No patient-specific recommendation is made.
Sources
These references support the concepts and methods used in the explanation above.