Nclexpn Quiz: Medication Dosage Calculations

What this quiz covers

This quiz focuses on Medication Dosage Calculations, giving you a quick way to practice the rules, question types, and explanations that matter most for Nclexpn.

How to use this quiz

Try each quiz question before looking at the correct answer. Use the explanations to review missed ideas, then come back to similar questions until the pattern feels familiar.

Question 1

1. 0.5 tablet
2. 1 tablet
3. 4 tablets
4. 2 tablets (correct answer)

Explanation: This question tests medication dosage calculation skills. The key calculation principle is unit conversion from grams to milligrams and then to number of tablets. The correct answer of 2 tablets is calculated by converting 0.5 g to 500 mg and dividing by 250 mg per tablet (500 / 250 = 2). Choice A (1 tablet) results from not converting grams; choice C (0.5 tablet) from halving erroneously; choice D (4 tablets) from misconversion. The formula used is number of tablets = (ordered dose in mg) / (mg per tablet). Convert all units to match before calculating. A transferable strategy is to always convert to the smallest unit (e.g., mg) before dividing by the available strength.

Question 2

1. 10.1 mL per dose
2. 20.3 mL per dose
3. 2.0 mL per dose
4. 5.1 mL per dose (correct answer)

Explanation: This question tests medication dosage calculation skills. The key calculation principle is weight-based dosing with division for frequency and conversion to volume using the suspension concentration. The correct answer of 5.1 mL per dose is calculated by first determining the daily dose (45 mg/kg/day × 18 kg = 810 mg/day), dividing by 2 for q12h (405 mg/dose), and then converting to volume ((405 mg / 400 mg) × 5 mL ≈ 5.1 mL). Choice A (2.0 mL) results from using the safe range minimum without division; choice C (10.1 mL) from not dividing the daily dose; choice D (20.3 mL) from using the full daily dose without conversion. The formula used is dose required = (prescribed mg/kg/day × weight) / doses per day, then volume = (dose / concentration) × volume per concentration unit. Verify the dose is within the safe range of 40–50 mg/kg/day before administration. A transferable strategy is to always calculate the total daily dose first, divide by the number of doses, and then apply the concentration ratio for accurate volume.

Question 3

1. 0.4 mL
2. 0.6 mL (correct answer)
3. 1.0 mL
4. 1.6 mL

Explanation: This question tests medication dosage calculation skills. The key calculation principle is dose conversion to volume using vial concentration. The correct answer of 0.6 mL is calculated by dividing 6 mg by 10 mg/mL (6 / 10 = 0.6 mL). Choice A (0.4 mL) results from using 4 mg; choice C (1.0 mL) from not dividing; choice D (1.6 mL) from miscalculation. The formula used is volume = ordered / concentration. Use appropriate syringe. A transferable strategy is to divide dose by mg per mL directly.

Question 4

1. 0.75 tablet
2. 2 tablets
3. 1 tablet
4. 3 tablets (correct answer)

Explanation: This question tests medication dosage calculation skills. The key calculation principle is unit conversion from mg to mcg and then to number of tablets. The correct answer of 3 tablets is calculated by converting 0.075 mg to 75 mcg and dividing by 25 mcg (75 / 25 = 3). Choice A (1 tablet) results from not converting; choice B (2 tablets) from using 37.5; choice D (0.75 tablet) from inverting. The formula used is number of tablets = (ordered in mcg) / (mcg per tablet). Convert to mcg. A transferable strategy is to standardize units to mcg for thyroid medications.

Question 5

1. 0.5 mL
2. 1 mL (correct answer)
3. 0.1 mL
4. 2 mL

Explanation: This question tests medication dosage calculation skills, specifically converting units and determining the volume to administer based on the prescribed dose and available concentration. The key calculation principle involves unit conversion from milligrams to micrograms and then applying the dosage formula to find the volume. The correct answer, 1 mL, is calculated by converting 1 mg to 1,000 mcg and dividing by the concentration of 1,000 mcg/mL, resulting in exactly 1 mL. Option A (0.1 mL) results from mistakenly converting 1 mg to 100 mcg instead of 1,000 mcg; option B (0.5 mL) arises from incorrectly halving the converted dose or misapplying the concentration; and option D (2 mL) occurs from doubling the dose or confusing mg with mcg without proper conversion. The calculation principle used is to first ensure unit consistency: 1 mg = 1,000 mcg. Then, apply the formula: volume (mL) = desired dose (mcg) / concentration (mcg/mL) = 1,000 mcg / 1,000 mcg/mL = 1 mL. A transferable calculation strategy is to always verify unit conversions using known equivalents (e.g., 1 mg = 1,000 mcg) and double-check the math to avoid common errors like misplaced decimals.

Question 6

1. 13.3 mL per dose
2. 6.7 mL per dose (correct answer)
3. 10.0 mL per dose
4. 3.3 mL per dose

Explanation: This question tests medication dosage calculation skills. The key calculation principle is weight-based daily dosing divided by frequency and converted to volume. The correct answer of 6.7 mL is calculated by daily dose (10 mg/kg/day × 30 kg = 300 mg/day), per dose (300 / 3 = 100 mg), volume ((100 / 75) × 5 ≈ 6.7 mL). Choice A (3.3 mL) results from halving; choice C (13.3 mL) from not dividing; choice D (10.0 mL) from misconcentration. The formula used is per dose = (mg/kg/day × weight) / doses, volume = (dose / mg) × mL. Verify safe range. A transferable strategy is to compute daily total first, divide by doses, then apply concentration ratio.

Question 7

1. 15 mL
2. 5 mL
3. 10 mL (correct answer)
4. 20 mL

Explanation: This question tests medication dosage calculation skills. The key calculation principle is conversion from mEq to volume using liquid concentration. The correct answer of 10 mL is calculated by (20 mEq / 10 mEq) × 5 mL = 10 mL. Choice A (5 mL) results from not multiplying; choice C (15 mL) from adding; choice D (20 mL) from doubling. The formula used is volume = (ordered / conc) × volume per conc. Dilute as needed. A transferable strategy is to use ratio: ordered mEq to available mEq as x mL to 5 mL.

Question 8

1. 1 tablet
2. 2 tablets
3. 1.5 tablets
4. 0.5 tablet (correct answer)

Explanation: This question tests medication dosage calculation skills. The key calculation principle is dose conversion to fraction of a tablet. The correct answer of 0.5 tablet is calculated by dividing ordered (25 mg) by available (50 mg), yielding 25 / 50 = 0.5. Choice A (1 tablet) results from not dividing; choice B (2 tablets) from inverting; choice D (1.5 tablets) from miscalculation. The formula used is number of tablets = ordered / available. Check if scored. A transferable strategy is to set up as a ratio: ordered : available :: x : 1 tablet.

Question 9

1. 20 mL
2. 2.5 mL
3. 10 mL (correct answer)
4. 5 mL

Explanation: This question tests medication dosage calculation skills. The key calculation principle is weight-based dosing converted to volume using the liquid concentration. The correct answer of 10 mL is calculated by determining the dose (10 mg/kg × 20 kg = 200 mg) and converting ((200 mg / 100 mg) × 5 mL = 10 mL). Choice A (5 mL) results from halving the dose; choice C (20 mL) from doubling; choice D (2.5 mL) from using half weight. The formula used is dose = mg/kg × weight, then volume = (dose / concentration) × volume per concentration. Verify the daily maximum is not exceeded. A transferable strategy is to calculate the mg dose first, then apply the ratio of available concentration to find volume.

Question 10

1. 0.5 tablet
2. 1 tablet
3. 1.5 tablets
4. 2 tablets (correct answer)

Explanation: Using the standard dosage formula: (Desired dose / Have on hand) x Quantity. (0.5 mg / 0.25 mg) x 1 tablet = 2 tablets. Each tablet contains 0.25 mg, and two tablets are required to deliver the prescribed 0.5 mg dose.

Question 11

1. 0.3 mL
2. 3.2 mL
3. 7.8 mL (correct answer)
4. 8.0 mL

Explanation: Using the formula: (Desired / Have) x Quantity. (250 mg / 160 mg) x 5 mL = 7.8125 mL. Rounded to the nearest tenth: 7.8 mL.

Question 12

1. 31 gtt/min (correct answer)
2. 33 gtt/min
3. 125 gtt/min
4. 188 gtt/min

Explanation: Formula: (Total Volume x Drop Factor) / Total Time in minutes. Total time: 8 hours x 60 min/hour = 480 minutes. (1,000 mL x 15 gtt/mL) / 480 min = 15,000 / 480 = 31.25 gtt/min. Rounded to the nearest whole number: 31 gtt/min. Choice C (125 mL/hr) represents the hourly infusion rate, not the drip rate — a common calculation error when the drop factor is not applied.

Question 13

1. 50 mL/hour
2. 100 mL/hour
3. 200 mL/hour (correct answer)
4. 300 mL/hour

Explanation: Formula: (Volume / Time in minutes) x 60 minutes/hour. (100 mL / 30 min) x 60 min/hour = 200 mL/hour. The infusion pump requires an hourly rate setting, so the 30-minute volume must be converted to its equivalent hourly rate. Infusing 100 mL in 30 minutes is equivalent to infusing 200 mL in 60 minutes.

Question 14

1. 0.5 mL (correct answer)
2. 1 mL
3. 1.5 mL
4. 2 mL

Explanation: Formula: (Desired / Have) x Quantity. (5,000 units / 10,000 units) x 1 mL = 0.5 mL. Because heparin is a high-alert medication, any calculated volume should be independently verified by a second nurse before administration.

Question 15

1. 250 to 500 mg/day
2. 500 to 1,000 mg/day
3. 625 to 1,250 mg/day (correct answer)
4. 1,250 to 2,500 mg/day

Explanation: Using the safe dose range of 25 to 50 mg/kg/day and the client's weight of 25 kg: Minimum: 25 mg/kg x 25 kg = 625 mg/day. Maximum: 50 mg/kg x 25 kg = 1,250 mg/day. Safe range: 625 to 1,250 mg/day. Choice A uses only the per-kg numbers (25 and 50) without multiplying by weight. Choice D doubles the correct answer, a common error from misreading the weight as 50 kg.

Question 16

1. The dose is within the safe range for this client.
2. The dose is too low to be effective for the infection.
3. The total daily dose exceeds the safe range for this client. (correct answer)
4. The frequency of every 8 hours is too often for a child.

Explanation: Every 8 hours means 3 doses in a 24-hour period. Total daily dose: 500 mg x 3 doses = 1,500 mg/day. The calculated maximum safe dose is 1,250 mg/day. 1,500 mg/day exceeds 1,250 mg/day — the prescribed order exceeds the safe dose range by 250 mg/day and must not be administered as written. This is a critical safety calculation that must be completed before any dose is administered. Choice A is incorrect — 1,500 > 1,250. Choice B is incorrect — 1,500 mg/day exceeds the maximum, it is not too low. Choice D is incorrect — every 8 hours (three times daily) is a standard dosing frequency consistent with the safe range parameters provided.

Question 17

1. 0.5 mL (correct answer)
2. 1 mL
3. 2 mL
4. 2.5 mL

Explanation: Formula: (Desired / Have) x Quantity. (25 mg / 50 mg) x 1 mL = 0.5 mL. The prescribed dose is half the available concentration, so half the volume (0.5 mL) is required.

Question 18

1. 0.7 mL
2. 1.2 mL
3. 1.5 mL (correct answer)
4. 2.5 mL

Explanation: Formula: (Desired / Have) x Quantity. (15 mg / 10 mg) x 1 mL = 1.5 mL. As a high-alert opioid medication, this calculation should be independently verified by a second nurse before administration per most facility protocols.

Question 19

1. 3 mL
2. 5 mL
3. 10 mL
4. 15 mL (correct answer)

Explanation: Formula: (Desired / Have) x Quantity. (30 mg / 10 mg) x 5 mL = 15 mL. Choice A (3 mL) results from dividing 30 by 10 without applying the quantity multiplier. Choice B (5 mL) represents 10 mg, not 30 mg. Choice C (10 mL) represents 20 mg.

Question 20

1. 0.5 tablet
2. 1 tablet
3. 2 tablets (correct answer)
4. 4 tablets

Explanation: Formula: (Desired / Have) x Quantity. (0.25 mg / 0.125 mg) x 1 tablet = 2 tablets. The prescribed dose is exactly double the available tablet strength, requiring two tablets to deliver the ordered dose.