NEX Mathematical Calculations: Dosages and Solutions 3

Question 1

A child weighing 22 kg is prescribed a medication at 10 mg/kg/day in 4 divided doses. The medication is available as a suspension of 125 mg/5 mL. How many mL should be given per dose?

Accepted Answer

4.4 mL

Answer

Daily dose: 22 kg × 10 mg/kg = 220 mg. Per dose: 220 ÷ 4 = 55 mg. Volume: (55/125) × 5 = 2.2 mL. Wait — let me recalculate: (55 ÷ 125) × 5 = 0.44 × 5 = 2.2 mL.

Question 2

A nurse is to administer 2 liters of IV fluid over 24 hours using a microdrip set (60 gtt/mL). What is the drip rate?

Accepted Answer

83 gtt/min

Answer

Flow rate = (2000 mL × 60 gtt/mL) / (24 × 60 min) = 120,000 / 1,440 = 83.3, rounded to 83 gtt/min.

Question 3

Convert 0.25 grams to milligrams.

Accepted Answer

250 mg

Answer

To convert grams to milligrams, multiply by 1,000: 0.25 g × 1,000 = 250 mg.

Question 4

A physician orders dopamine at 5 mcg/kg/min for a 70 kg patient. The solution contains 400 mg of dopamine in 250 mL of D5W. What is the infusion rate in mL/hr?

Accepted Answer

13.1 mL/hr

Answer

Dose: 5 mcg/kg/min × 70 kg = 350 mcg/min. Convert to mg: 350/1000 = 0.35 mg/min. Concentration: 400 mg/250 mL = 1.6 mg/mL. Rate: 0.35/1.6 = 0.21875 mL/min × 60 = 13.1 mL/hr.

Question 5

How many tablets should be administered if the order reads 'Give 0.5 mg PO' and the available tablets are scored and contain 0.25 mg each?

Accepted Answer

2 tablets

Answer

Number of tablets = Desired dose / Available dose = 0.5 mg / 0.25 mg = 2 tablets.

(NEX) Nursing Entrance Exam Practice Test

(NEX) Nursing Entrance Exam Practice Test

NEX Mathematical Calculations: Dosages and Solutions 3