Worked example: learn the method
Ungraded teaching example with different numbers from the practice exercise. For study only, not clinical use.
225 mL is infusing at 25 mL/hr. How many hours will the infusion take?
Total volume ÷ rate = infusion time in hours
- Divide the volume by the rate: 225 mL ÷ 25 mL/hr = 9 hours
- Units cancel: mL ÷ (mL/hr) leaves hours — the unit you were asked for.
- Sense-check by multiplying back: 9 hours × 25 mL/hr = 225 mL, which is the volume you started with.
Example result: 9 hours. Round to the nearest tenth of an hour.
Common mistake to avoid: After dividing volume by rate, convert the fractional hour to minutes; 0.5 hour is 30 minutes, not 50 minutes.
Dosage formulas · Unit conversion reference
Problem
500 mL is infusing at 50 mL/hr. How many hours will the infusion take?
Round to the nearest tenth of an hour.
These are practice problems for exam preparation. Every number in them is generated by CARE for teaching purposes — nothing here is a real order and nothing here is a clinical dosing tool. Do not use this page to work out a dose for a real patient: use your facility's policy, the actual order, and an independent double-check where your policy requires one.
Medication calculations also appear inside real exam practice, mixed with everything else and scored the same way. Try a free quiz drawn from the actual question bank.
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