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Practice Set 1 - Review by Topic

Instructions

Work through each problem independently before revealing the answer. Write out every step using unit cancellation.

This set is organized by topic to help you identify specific areas that need review.

How to Use This Set

  • Attempt every problem before checking the answer
  • If you get a problem wrong, identify exactly which step went wrong in your unit cancellation chain
  • Note which topics give you the most trouble and review the relevant module before attempting Practice Set 2

Section 1 — Unit Conversions

Problem 1

Convert 2.5 g to mg.

Answer
\[2.5 \cancel{\text{ g}} \times \frac{1000 \text{ mg}}{1 \cancel{\text{ g}}} = 2500 \text{ mg}\]

Problem 2

Convert 750 mcg to mg.

Answer
\[750 \cancel{\text{ mcg}} \times \frac{1 \text{ mg}}{1000 \cancel{\text{ mcg}}} = 0.75 \text{ mg}\]

Problem 3

A patient weighs 143 lb. Convert to kg.

Answer
\[143 \cancel{\text{ lb}} \times \frac{1 \text{ kg}}{2.2 \cancel{\text{ lb}}} = 65 \text{ kg}\]

Section 2 — Oral Tablets

Problem 4

Order: metoprolol 100 mg orally Stock: 50 mg per tablet How many tablets?

Answer
\[\frac{100 \cancel{\text{ mg}}}{1} \times \frac{1 \text{ tablet}}{50 \cancel{\text{ mg}}} = 2 \text{ tablets}\]

Problem 5

Order: warfarin 7.5 mg orally Stock: 5 mg per tablet How many tablets?

Answer
\[\frac{7.5 \cancel{\text{ mg}}}{1} \times \frac{1 \text{ tablet}}{5 \cancel{\text{ mg}}} = 1.5 \text{ tablets}\]

Verify tablet is scored before splitting.

Problem 6

Order: levothyroxine 0.15 mg orally Stock: 50 mcg per tablet How many tablets?

Answer
\[\frac{0.15 \cancel{\text{ mg}}}{1} \times \frac{1000 \cancel{\text{ mcg}}}{1 \cancel{\text{ mg}}} \times \frac{1 \text{ tablet}}{50 \cancel{\text{ mcg}}} = 3 \text{ tablets}\]

Section 3 — Oral Liquids

Problem 7

Order: amoxicillin 375 mg orally Stock: 250 mg/5 mL How many mL?

Answer
\[\frac{375 \cancel{\text{ mg}}}{1} \times \frac{5 \text{ mL}}{250 \cancel{\text{ mg}}} = 7.5 \text{ mL}\]

Problem 8

Order: ibuprofen 0.4 g orally Stock: 200 mg/5 mL How many mL?

Answer
\[\frac{0.4 \cancel{\text{ g}}}{1} \times \frac{1000 \cancel{\text{ mg}}}{1 \cancel{\text{ g}}} \times \frac{5 \text{ mL}}{200 \cancel{\text{ mg}}} = 10 \text{ mL}\]

Problem 9

Order: morphine 7.5 mg orally Stock: 10 mg/5 mL How many mL?

Answer
\[\frac{7.5 \cancel{\text{ mg}}}{1} \times \frac{5 \text{ mL}}{10 \cancel{\text{ mg}}} = 3.75 \text{ mL}\]

Round to nearest tenth: 3.8 mL


Section 4 — Weight-Based Dosing (Adult)

Problem 10

Order: gentamicin 5 mg/kg IV Patient weight: 80 kg Stock: 40 mg/mL How many mL?

Answer
\[\frac{80 \cancel{\text{ kg}}}{1} \times \frac{5 \cancel{\text{ mg}}}{1 \cancel{\text{ kg}}} \times \frac{1 \text{ mL}}{40 \cancel{\text{ mg}}} = 10 \text{ mL}\]

Problem 11

Order: vancomycin 15 mg/kg IV Patient weight: 176 lb Stock: 500 mg/10 mL How many mL?

Answer

Convert weight: [176 \cancel{\text{ lb}} \times \frac{1 \text{ kg}}{2.2 \cancel{\text{ lb}}} = 80 \text{ kg}]

Full chain: [\frac{80 \cancel{\text{ kg}}}{1} \times \frac{15 \cancel{\text{ mg}}}{1 \cancel{\text{ kg}}} \times \frac{10 \text{ mL}}{500 \cancel{\text{ mg}}} = 24 \text{ mL}]

Problem 12

Order: ibuprofen 10 mg/kg orally, max 600 mg Patient weight: 85 kg Stock: 200 mg/5 mL How many mL?

Answer

Calculated dose: [85 \cancel{\text{ kg}} \times \frac{10 \text{ mg}}{1 \cancel{\text{ kg}}} = 850 \text{ mg}]

850 mg exceeds max of 600 mg — use 600 mg

Volume: [\frac{600 \cancel{\text{ mg}}}{1} \times \frac{5 \text{ mL}}{200 \cancel{\text{ mg}}} = 15 \text{ mL}]

Problem 13

Order: morphine 0.1 mg/kg IV PRN Patient weight: 154 lb Stock: 10 mg/mL How many mL?

Answer

Convert weight: [154 \cancel{\text{ lb}} \times \frac{1 \text{ kg}}{2.2 \cancel{\text{ lb}}} = 70 \text{ kg}]

Full chain: [\frac{70 \cancel{\text{ kg}}}{1} \times \frac{0.1 \cancel{\text{ mg}}}{1 \cancel{\text{ kg}}} \times \frac{1 \text{ mL}}{10 \cancel{\text{ mg}}} = 0.7 \text{ mL}]


Section 5 — Weight-Based Dosing (Pediatric)

Problem 14

Order: amoxicillin 25 mg/kg orally Patient: child weighing 22 kg Stock: 250 mg/5 mL How many mL?

Answer
\[\frac{22 \cancel{\text{ kg}}}{1} \times \frac{25 \cancel{\text{ mg}}}{1 \cancel{\text{ kg}}} \times \frac{5 \text{ mL}}{250 \cancel{\text{ mg}}} = 11 \text{ mL}\]

Problem 15

Order: paracetamol 15 mg/kg orally, max 500 mg Patient: child weighing 40 kg Stock: 250 mg/5 mL How many mL?

Answer

Calculated dose: [40 \cancel{\text{ kg}} \times \frac{15 \text{ mg}}{1 \cancel{\text{ kg}}} = 600 \text{ mg}]

600 mg exceeds max of 500 mg — use 500 mg

Volume: [\frac{500 \cancel{\text{ mg}}}{1} \times \frac{5 \text{ mL}}{250 \cancel{\text{ mg}}} = 10 \text{ mL}]

Problem 16

Order: penicillin V 50 mg/kg/day orally divided every 6 hours Patient: child weighing 20 kg Stock: 125 mg/5 mL How many mL per dose?

Answer

Total daily dose: [20 \cancel{\text{ kg}} \times \frac{50 \text{ mg}}{1 \cancel{\text{ kg}}} = 1000 \text{ mg/day}]

Single dose (4 doses/day): [1000 \div 4 = 250 \text{ mg per dose}]

Volume: [\frac{250 \cancel{\text{ mg}}}{1} \times \frac{5 \text{ mL}}{125 \cancel{\text{ mg}}} = 10 \text{ mL}]


Section 6 — IV Flow Rates

Problem 17

Order: 1000 mL 0.9% NaCl over 8 hours What is the flow rate in mL/hr?

Answer
\[\frac{1000 \text{ mL}}{8 \text{ hr}} = 125 \text{ mL/hr}\]

Problem 18

Order: 250 mL over 45 minutes What is the flow rate in mL/hr?

Answer

Convert time: [45 \cancel{\text{ min}} \times \frac{1 \text{ hr}}{60 \cancel{\text{ min}}} = 0.75 \text{ hr}]

Rate: [\frac{250 \text{ mL}}{0.75 \text{ hr}} = 333.3 \text{ mL/hr}]

Round to: 333 mL/hr

Problem 19

A 1000 mL bag is running at 150 mL/hr. After 3 hours how much fluid remains and how much longer will it run?

Answer

Volume infused: [150 \text{ mL/hr} \times 3 \text{ hr} = 450 \text{ mL}]

Volume remaining: [1000 - 450 = 550 \text{ mL}]

Time remaining: [\frac{550 \text{ mL}}{150 \text{ mL/hr}} = 3.67 \text{ hr}]

Convert decimal: [0.67 \times 60 = 40 \text{ min}]

3 hours and 40 minutes remaining


Section 7 — Drip Rates

Problem 20

Order: 1000 mL over 8 hours Tubing: 20 gtt/mL What is the drip rate in gtt/min?

Answer

Convert time: [8 \times 60 = 480 \text{ min}]

Calculate: [\frac{1000 \text{ mL}}{480 \text{ min}} \times 20 \text{ gtt/mL} = 41.7 \text{ gtt/min}]

Round to: 42 gtt/min

Problem 21

Rate: 60 mL/hr Tubing: 60 gtt/mL (microdrip) What is the drip rate?

Answer

Using microdrip shortcut:

60 gtt/min


Section 8 — IV Medications

Problem 22

Order: vancomycin 1000 mg in 250 mL over 90 minutes What is the flow rate in mL/hr?

Answer

Convert time: [90 \cancel{\text{ min}} \times \frac{1 \text{ hr}}{60 \cancel{\text{ min}}} = 1.5 \text{ hr}]

Rate: [\frac{250 \text{ mL}}{1.5 \text{ hr}} = 166.7 \text{ mL/hr}]

Round to: 167 mL/hr

Problem 23

Order: heparin 1000 units/hr IV Stock: 25,000 units in 500 mL 0.9% NaCl What is the flow rate in mL/hr?

Answer

Concentration: [\frac{25{,}000 \text{ units}}{500 \text{ mL}} = 50 \text{ units/mL}]

Flow rate: [\frac{1000 \text{ units/hr}}{50 \text{ units/mL}} = 20 \text{ mL/hr}]

Problem 24

Order: dopamine 5 mcg/kg/min IV Patient weight: 60 kg Stock: dopamine 400 mg in 250 mL D5W What is the flow rate in mL/hr?

Answer

Dose per minute: [60 \cancel{\text{ kg}} \times \frac{5 \text{ mcg}}{1 \cancel{\text{ kg}} \cdot \text{min}} = 300 \text{ mcg/min}]

Convert to mg/hr: [300 \cancel{\text{ mcg/min}} \times \frac{1 \cancel{\text{ mg}}}{1000 \cancel{\text{ mcg}}} \times \frac{60 \text{ min}}{1 \text{ hr}} = 18 \text{ mg/hr}]

Concentration: [\frac{400 \text{ mg}}{250 \text{ mL}} = 1.6 \text{ mg/mL}]

Flow rate: [\frac{18 \text{ mg/hr}}{1.6 \text{ mg/mL}} = 11.25 \text{ mL/hr}]

Round to: 11 mL/hr

Problem 25

An IV is running at 25 mL/hr. Stock: morphine 50 mg in 500 mL 0.9% NaCl What dose is the patient receiving per hour?

Answer

Concentration: [\frac{50 \text{ mg}}{500 \text{ mL}} = 0.1 \text{ mg/mL}]

Dose rate: [25 \text{ mL/hr} \times 0.1 \text{ mg/mL} = 2.5 \text{ mg/hr}]


How Did You Do?

  • 23-25 correct — excellent, you are ready for clinical practice
  • 20-22 correct — good, review the topics you missed
  • Below 20 — review the relevant modules before attempting Set 2

Remember — clinical competency requires 90% or higher. That means no more than 2 errors on a 25 question assessment.