TEST BANK BASED ON:
Calculating Drug Dosages
A Patient-Safe Approach to Nursing and Math
3rd Edition
• Author(s)Sandra Luz Martinez de Castillo;
Maryanne Werner-McCullough
1.
Chapter Reference
Chapter 1 — Section: Unit conversions & route
safety — Safety in Medication Administration
Stem
An order reads: Give 500 mcg PO. You have tablets
labeled 0.25 mg. How many tablets should you
administer?
,Options
A. 1 tablet
B. 2 tablets
C. 3 tablets
D. 0.5 tablet
Correct Answer
B
Rationales
• Correct (B): Convert units first. 500 mcg = 500 ÷
1000 = 0.5 mg. Available tablet = 0.25 mg.
Tablets needed = 0.5 mg ÷ 0.25 mg/tablet = 2
tablets.
• A (1 tablet): Error: treated 500 mcg as 0.25 mg
or forgot to convert mcg→mg (0.25 mg only, so
1 tablet = 250 mcg not 500 mcg).
• C (3 tablets): Error: arithmetic/over-estimation
(3 × 0.25 mg = 0.75 mg, giving 50% overdose).
• D (0.5 tablet): Error: inverted conversion (0.5
tablet × 0.25 mg = 0.125 mg = 125 mcg,
underdose).
,Teaching Point
Always convert units to the same base before
calculating dose.
2.
Chapter Reference
Chapter 1 — Section: IV infusion fundamentals —
Safety in Medication Administration
Stem
Order: D5W 1000 mL IV over 8 hours. What mL/hr
should you set on the infusion pump?
Options
A. 100 mL/hr
B. 125 mL/hr
C. 150 mL/hr
D. 83.3 mL/hr
Correct Answer
B
Rationales
, • Correct (B): mL/hr = total volume ÷ hours =
1000 mL ÷ 8 hr = 125 mL/hr.
• A (100 mL/hr): Mistake: divided by 10 instead of
8 (1000 ÷ 10 = 100).
• C (150 mL/hr): Mistake: likely misdivided (1000
÷ 6.67 ≈150) — wrong denominator.
• D (83.3 mL/hr): Mistake: used 12 hr or
converted incorrectly (1000 ÷ 12 = 83.33), not
the ordered 8 hours.
Teaching Point
Set pumps in mL/hr using total volume ÷ infusion
time (hours).
3.
Chapter Reference
Chapter 1 — Section: Manual drip rates (macrodrip)
— Safety in Medication Administration
Stem
Order: Infuse 500 mL IV over 4 hours using 20
Calculating Drug Dosages
A Patient-Safe Approach to Nursing and Math
3rd Edition
• Author(s)Sandra Luz Martinez de Castillo;
Maryanne Werner-McCullough
1.
Chapter Reference
Chapter 1 — Section: Unit conversions & route
safety — Safety in Medication Administration
Stem
An order reads: Give 500 mcg PO. You have tablets
labeled 0.25 mg. How many tablets should you
administer?
,Options
A. 1 tablet
B. 2 tablets
C. 3 tablets
D. 0.5 tablet
Correct Answer
B
Rationales
• Correct (B): Convert units first. 500 mcg = 500 ÷
1000 = 0.5 mg. Available tablet = 0.25 mg.
Tablets needed = 0.5 mg ÷ 0.25 mg/tablet = 2
tablets.
• A (1 tablet): Error: treated 500 mcg as 0.25 mg
or forgot to convert mcg→mg (0.25 mg only, so
1 tablet = 250 mcg not 500 mcg).
• C (3 tablets): Error: arithmetic/over-estimation
(3 × 0.25 mg = 0.75 mg, giving 50% overdose).
• D (0.5 tablet): Error: inverted conversion (0.5
tablet × 0.25 mg = 0.125 mg = 125 mcg,
underdose).
,Teaching Point
Always convert units to the same base before
calculating dose.
2.
Chapter Reference
Chapter 1 — Section: IV infusion fundamentals —
Safety in Medication Administration
Stem
Order: D5W 1000 mL IV over 8 hours. What mL/hr
should you set on the infusion pump?
Options
A. 100 mL/hr
B. 125 mL/hr
C. 150 mL/hr
D. 83.3 mL/hr
Correct Answer
B
Rationales
, • Correct (B): mL/hr = total volume ÷ hours =
1000 mL ÷ 8 hr = 125 mL/hr.
• A (100 mL/hr): Mistake: divided by 10 instead of
8 (1000 ÷ 10 = 100).
• C (150 mL/hr): Mistake: likely misdivided (1000
÷ 6.67 ≈150) — wrong denominator.
• D (83.3 mL/hr): Mistake: used 12 hr or
converted incorrectly (1000 ÷ 12 = 83.33), not
the ordered 8 hours.
Teaching Point
Set pumps in mL/hr using total volume ÷ infusion
time (hours).
3.
Chapter Reference
Chapter 1 — Section: Manual drip rates (macrodrip)
— Safety in Medication Administration
Stem
Order: Infuse 500 mL IV over 4 hours using 20
