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
Chapter Reference: Chapter 1 — Safety in Medication
Administration; Section: Unit Conversion & Label Interpretation
Stem: A physician orders 125 mg of cefuroxime. The vial label
reads 250 mg per 5 mL. How many mL should the nurse
prepare?
A. 1.25 mL
B. 2.5 mL
C. 5 mL
D. 0.625 mL
Correct Answer: B
Rationales:
, • Correct (B): Use ratio: (Desired ÷ Available) × Volume =
(125 mg ÷ 250 mg) × 5 mL = 0.5 × 5 mL = 2.5 mL.
• A (1.25 mL): Represents halving the correct volume again
(125 mg ÷ 250 mg × 2.5 mL) — decimal placement error.
• C (5 mL): This gives the full vial volume (250 mg) instead of
the fraction needed for 125 mg.
• D (0.625 mL): Likely a misapplied conversion by dividing
result by 4 (decimal shift error).
Teaching Point: Always compute (desired ÷ available) ×
vehicle volume; check decimal placements.
2.
Chapter Reference: Chapter 1 — Safety in Medication
Administration; Section: Safe Decimal Use
Stem: An order reads “Give digoxin 0.125 mg PO.” Which
written dose is safest to document to avoid a tenfold error?
A. 0.125 mg
B. .125 mg
C. 0.13 mg
D. 0.1250 mg
Correct Answer: A
Rationales:
• Correct (A): Leading zero used before the decimal (0.125
mg) is the recommended safe format.
, • B ( .125 mg ): Missing leading zero — increases risk of
misreading as 1.25 mg (tenfold error).
• C (0.13 mg): Rounded value — introduces unnecessary
rounding for narrow therapeutic index drug.
• D (0.1250 mg): Trailing zeros should be avoided because
they imply greater precision and risk misinterpretation
during conversions.
Teaching Point: Always use a leading zero before decimals;
avoid trailing zeros.
3.
Chapter Reference: Chapter 1 — Safety in Medication
Administration; Section: IV Infusion Rate (mL/hr)
Stem: An IV bag contains 1 g of antibiotic in 250 mL. The order
is to infuse the antibiotic over 2 hours. What pump rate (mL/hr)
should be programmed?
A. 62.5 mL/hr
B. 125 mL/hr
C. 250 mL/hr
D. 83.3 mL/hr
Correct Answer: B
Rationales:
• Correct (B): Total volume ÷ time (hr) = 250 mL ÷ 2 hr = 125
mL/hr. Drug amount (1 g) irrelevant to mL/hr when the
bag volume and time are given.
, • A (62.5 mL/hr): Mistake: divided 125 mL/hr by 2 (double-
divided).
• C (250 mL/hr): Infusing entire bag in 1 hour, not the
ordered 2 hours.
• D (83.3 mL/hr): Likely computed as 250 mL ÷ 3 hr (wrong
time denominator) or confusion with minutes.
Teaching Point: For pump programming, divide total mL by
hours ordered.
4.
Chapter Reference: Chapter 1 — Safety in Medication
Administration; Section: Drop Rate Calculations (gtt/min)
Stem: Order: Infuse 500 mL D5W over 4 hours using tubing with
a drop factor of 15 gtt/mL. What is the drip rate (gtt/min)?
A. 31 gtt/min
B. 19 gtt/min
C. 62 gtt/min
D. 125 gtt/min
Correct Answer: A
Rationales:
• Correct (A): mL/min = 500 mL ÷ (4 hr × 60 min) = 500 ÷ 240
= 2.08333 mL/min. gtt/min = 2.08333 × 15 = 31.25, round
to 31 gtt/min (whole drops).
• B (19 gtt/min): Likely used 10 gtt/mL drop factor instead of
15 gtt/mL.
Calculating Drug Dosages
A Patient-Safe Approach to Nursing and Math
3rd Edition
• Author(s)Sandra Luz Martinez de Castillo;
Maryanne Werner-McCullough
Chapter Reference: Chapter 1 — Safety in Medication
Administration; Section: Unit Conversion & Label Interpretation
Stem: A physician orders 125 mg of cefuroxime. The vial label
reads 250 mg per 5 mL. How many mL should the nurse
prepare?
A. 1.25 mL
B. 2.5 mL
C. 5 mL
D. 0.625 mL
Correct Answer: B
Rationales:
, • Correct (B): Use ratio: (Desired ÷ Available) × Volume =
(125 mg ÷ 250 mg) × 5 mL = 0.5 × 5 mL = 2.5 mL.
• A (1.25 mL): Represents halving the correct volume again
(125 mg ÷ 250 mg × 2.5 mL) — decimal placement error.
• C (5 mL): This gives the full vial volume (250 mg) instead of
the fraction needed for 125 mg.
• D (0.625 mL): Likely a misapplied conversion by dividing
result by 4 (decimal shift error).
Teaching Point: Always compute (desired ÷ available) ×
vehicle volume; check decimal placements.
2.
Chapter Reference: Chapter 1 — Safety in Medication
Administration; Section: Safe Decimal Use
Stem: An order reads “Give digoxin 0.125 mg PO.” Which
written dose is safest to document to avoid a tenfold error?
A. 0.125 mg
B. .125 mg
C. 0.13 mg
D. 0.1250 mg
Correct Answer: A
Rationales:
• Correct (A): Leading zero used before the decimal (0.125
mg) is the recommended safe format.
, • B ( .125 mg ): Missing leading zero — increases risk of
misreading as 1.25 mg (tenfold error).
• C (0.13 mg): Rounded value — introduces unnecessary
rounding for narrow therapeutic index drug.
• D (0.1250 mg): Trailing zeros should be avoided because
they imply greater precision and risk misinterpretation
during conversions.
Teaching Point: Always use a leading zero before decimals;
avoid trailing zeros.
3.
Chapter Reference: Chapter 1 — Safety in Medication
Administration; Section: IV Infusion Rate (mL/hr)
Stem: An IV bag contains 1 g of antibiotic in 250 mL. The order
is to infuse the antibiotic over 2 hours. What pump rate (mL/hr)
should be programmed?
A. 62.5 mL/hr
B. 125 mL/hr
C. 250 mL/hr
D. 83.3 mL/hr
Correct Answer: B
Rationales:
• Correct (B): Total volume ÷ time (hr) = 250 mL ÷ 2 hr = 125
mL/hr. Drug amount (1 g) irrelevant to mL/hr when the
bag volume and time are given.
, • A (62.5 mL/hr): Mistake: divided 125 mL/hr by 2 (double-
divided).
• C (250 mL/hr): Infusing entire bag in 1 hour, not the
ordered 2 hours.
• D (83.3 mL/hr): Likely computed as 250 mL ÷ 3 hr (wrong
time denominator) or confusion with minutes.
Teaching Point: For pump programming, divide total mL by
hours ordered.
4.
Chapter Reference: Chapter 1 — Safety in Medication
Administration; Section: Drop Rate Calculations (gtt/min)
Stem: Order: Infuse 500 mL D5W over 4 hours using tubing with
a drop factor of 15 gtt/mL. What is the drip rate (gtt/min)?
A. 31 gtt/min
B. 19 gtt/min
C. 62 gtt/min
D. 125 gtt/min
Correct Answer: A
Rationales:
• Correct (A): mL/min = 500 mL ÷ (4 hr × 60 min) = 500 ÷ 240
= 2.08333 mL/min. gtt/min = 2.08333 × 15 = 31.25, round
to 31 gtt/min (whole drops).
• B (19 gtt/min): Likely used 10 gtt/mL drop factor instead of
15 gtt/mL.
