NMC CBT NMC-CBT Drug Calculations and Numeracy 3 — Questions and Answers
Question 1: A patient requires dopamine at 5 mcg/kg/min. The patient weighs 70 kg. Dopamine 400 mg is in 250 mL of dextrose. What is the infusion rate in mL/hr?
- 13.1 mL/hr (Correct answer)
- 16.4 mL/hr
- 10.5 mL/hr
- 20.0 mL/hr
Correct answer: 13.1 mL/hr
Dose = 5 × 70 = 350 mcg/min; concentration = 400,000 mcg ÷ 250 mL = 1600 mcg/mL; rate = 350 ÷ 1600 × 60 ≈ 13.1 mL/hr.
Question 2: A patient receives 1 litre of Hartmann's solution over 8 hours via a burette (60 drops/mL). What is the drip rate?
- 100 drops/min
- 115 drops/min
- 125 drops/min (Correct answer)
- 130 drops/min
Correct answer: 125 drops/min
(1000 × 60) ÷ (8 × 60) = 60,000 ÷ 480 = 125 drops/min.
Question 3: Warfarin 3.5 mg is prescribed. Tablets come in 0.5 mg and 5 mg strengths. What is the most appropriate combination?
- Seven 0.5 mg tablets (Correct answer)
- One 5 mg and three 0.5 mg tablets — take the 5 mg only
- One 5 mg tablet minus 0.5 mg = do not use
- One 0.5 mg tablet and one 5 mg tablet is too much
Correct answer: Seven 0.5 mg tablets
3.5 mg ÷ 0.5 mg = 7 tablets of 0.5 mg is the safest single-strength approach.
Question 4: A patient is prescribed gentamicin 5 mg/kg as a single daily dose. The patient weighs 85 kg. Available is gentamicin 80 mg/2 mL. How many mL are required?
- 8.5 mL
- 10.6 mL (Correct answer)
- 12.8 mL
- 5.3 mL
Correct answer: 10.6 mL
Dose = 5 × 85 = 425 mg; concentration = 40 mg/mL; volume = 425 ÷ 40 = 10.625 ≈ 10.6 mL.
Question 5: Convert 0.05 grams to micrograms.
- 500 mcg
- 5,000 mcg
- 50,000 mcg (Correct answer)
- 500,000 mcg
Correct answer: 50,000 mcg
0.05 g × 1,000 = 50 mg × 1,000 = 50,000 mcg.
Question 6: An insulin infusion runs at 4 units/hr. The syringe contains 50 units of insulin in 50 mL of 0.9% saline. At what rate (mL/hr) should the pump be set?
- 2 mL/hr
- 4 mL/hr (Correct answer)
- 8 mL/hr
- 1 mL/hr
Correct answer: 4 mL/hr
Concentration = 50 units ÷ 50 mL = 1 unit/mL; 4 units/hr ÷ 1 unit/mL = 4 mL/hr.
Question 7: A nurse draws up 0.4 mL from an ampoule of atropine 600 mcg/mL. How many micrograms has she prepared?
- 150 mcg
- 200 mcg
- 240 mcg (Correct answer)
- 300 mcg
Correct answer: 240 mcg
0.4 mL × 600 mcg/mL = 240 mcg.
NMC CBT NMC-CBT Drug Calculations and Numeracy 3
A patient requires dopamine at 5 mcg/kg/min.
The patient weighs 70 kg.
Dopamine 400 mg is in 250 mL of dextrose.
What is the infusion rate in mL/hr?