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
Stem: A prescription reads: Give 2,500 micrograms
(mcg) of Drug X IV. The vial label shows Drug X 1,000
mcg/mL. How many milligrams (mg) will the nurse
document as the dose administered?
Options:
A. 0.25 mg
B. 2.5 mg
,C. 25 mg
D. 250 mg
Correct Answer: B
Rationales:
• Correct (B — 2.5 mg): Convert mcg → mg using
1,000 mcg = 1 mg. Calculation: 2,500 mcg ÷
1,000 = 2.5 mg. Step-by-step: 2,500 ÷ 1,000 =
2.5.
• A (0.25 mg): Decimal place error — divided by
10,000 instead of 1,000 (2,500 ÷ 10,000 = 0.25).
• C (25 mg): Multiplied by 10 instead of dividing
(2,500 ÷ 100 = 25) — wrong conversion factor.
• D (250 mg): Off by two decimal places (2,500 ÷
10 = 250) — major unit misplacement.
Teaching Point: Always convert micrograms to
milligrams by dividing by 1,000.
2.
,Chapter 1 — Section 1.4: Dose Calculation Formula
(D/H × V)
Stem: Order: Give 250 mg cefazolin IM. Available:
cefazolin 500 mg in 10 mL vial. How many milliliters
should be administered?
Options:
A. 2.5 mL
B. 5 mL
C. 10 mL
D. 0.5 mL
Correct Answer: B
Rationales:
• Correct (B — 5 mL): Use D/H × V. D = desired
dose 250 mg; H = strength on hand 500 mg; V =
volume of vial 10 mL. Calculation: (250/500) ×
10 = 0.5 × 10 = 5 mL.
• A (2.5 mL): Likely calculated (250/500) × 5 —
used half the vial volume incorrectly.
, • C (10 mL): Administering entire vial (error:
assumed D equals H).
• D (0.5 mL): Decimal shift error (divided by 10
incorrectly).
Teaching Point: Apply D/H × V and keep track of
decimal placement.
3.
Chapter 1 — Section 1.5: Pediatric Weight-Based
Dosing
Stem: A child weighs 12 kg. Order: acetaminophen 7
mg/kg PO single dose. What is the correct dose in
mg?
Options:
A. 42 mg
B. 84 mg
C. 7 mg
D. 120 mg
Calculating Drug Dosages
A Patient-Safe Approach to Nursing and Math
3rd Edition
• Author(s)Sandra Luz Martinez de Castillo;
Maryanne Werner-McCullough
Stem: A prescription reads: Give 2,500 micrograms
(mcg) of Drug X IV. The vial label shows Drug X 1,000
mcg/mL. How many milligrams (mg) will the nurse
document as the dose administered?
Options:
A. 0.25 mg
B. 2.5 mg
,C. 25 mg
D. 250 mg
Correct Answer: B
Rationales:
• Correct (B — 2.5 mg): Convert mcg → mg using
1,000 mcg = 1 mg. Calculation: 2,500 mcg ÷
1,000 = 2.5 mg. Step-by-step: 2,500 ÷ 1,000 =
2.5.
• A (0.25 mg): Decimal place error — divided by
10,000 instead of 1,000 (2,500 ÷ 10,000 = 0.25).
• C (25 mg): Multiplied by 10 instead of dividing
(2,500 ÷ 100 = 25) — wrong conversion factor.
• D (250 mg): Off by two decimal places (2,500 ÷
10 = 250) — major unit misplacement.
Teaching Point: Always convert micrograms to
milligrams by dividing by 1,000.
2.
,Chapter 1 — Section 1.4: Dose Calculation Formula
(D/H × V)
Stem: Order: Give 250 mg cefazolin IM. Available:
cefazolin 500 mg in 10 mL vial. How many milliliters
should be administered?
Options:
A. 2.5 mL
B. 5 mL
C. 10 mL
D. 0.5 mL
Correct Answer: B
Rationales:
• Correct (B — 5 mL): Use D/H × V. D = desired
dose 250 mg; H = strength on hand 500 mg; V =
volume of vial 10 mL. Calculation: (250/500) ×
10 = 0.5 × 10 = 5 mL.
• A (2.5 mL): Likely calculated (250/500) × 5 —
used half the vial volume incorrectly.
, • C (10 mL): Administering entire vial (error:
assumed D equals H).
• D (0.5 mL): Decimal shift error (divided by 10
incorrectly).
Teaching Point: Apply D/H × V and keep track of
decimal placement.
3.
Chapter 1 — Section 1.5: Pediatric Weight-Based
Dosing
Stem: A child weighs 12 kg. Order: acetaminophen 7
mg/kg PO single dose. What is the correct dose in
mg?
Options:
A. 42 mg
B. 84 mg
C. 7 mg
D. 120 mg
