NCLEX-RN® Dosage Calculation Test Bank 2025 | Saunders Comprehensive Review Aligned | Pediatric & Adult Med Math, IV Flow Rates, mg/kg & Reconstitution Practice with Answers & Rationales

Saunders Comprehensive Review for the NCLEX-PN®
Examination
9th Edition
• Author(s)Linda Anne Silvestri; Angela Silvestri


TEST BANK


Questions 1–8 — Dosage by weight (mg/kg)
1)
A child weighs 22 lb. The physician orders gentamicin 2 mg/kg
IV stat. The vial on the unit contains 40 mg/mL. How many mL
should the nurse administer? (Use dimensional analysis; round
appropriately.)
A. 0.25 mL
B. 0.50 mL
C. 1.0 mL
D. 2.0 mL
Correct answer: B. 0.50 mL
Solution (step-by-step, dimensional analysis):
1. Convert pounds → kilograms: 22 lb÷2.20462=9.979 kg22\
\text{lb} \div 2.20462 = 9.979\
\text{kg}22 lb÷2.20462=9.979 kg.

, 2. Calculate dose in mg: 2 mg/kg×9.979 kg=19.958 mg2\
\text{mg/kg} \times 9.979\ \text{kg} = 19.958\
\text{mg}2 mg/kg×9.979 kg=19.958 mg.
3. Drug concentration: 40 mg per 1 mL. Use factor to get mL:
19.958 mg×1 mL40 mg=0.499 mL19.958\ \text{mg} \times
\frac{1\ \text{mL}}{40\ \text{mg}} = 0.499\
\text{mL}19.958 mg×40 mg1 mL=0.499 mL.
4. Rounding & administration: because the volume is <1 mL,
round to the hundredth for a tuberculin syringe → 0.50
mL.
Rationale: Correct conversion and dimensional cancellation
produce ≈0.499 mL → round to 0.50 mL. Option A (0.25 mL)
and C (1.0 mL) are calculation errors (halving or doubling the
correct volume). D (2.0 mL) is far too large and would overdose.


2)
An adult weighing 176 lb is ordered morphine 0.1 mg/kg IV.
Available concentration: 2 mg/mL. How many mL should be
given?
A. 1.5 mL
B. 4.0 mL
C. 8.0 mL
D. 0.8 mL
Correct answer: B. 4.0 mL

,Solution:
1. 176 lb÷2.20462=79.832 kg176\ \text{lb} \div 2.20462 =
79.832\ \text{kg}176 lb÷2.20462=79.832 kg.
2. Dose mg: 0.1 mg/kg×79.832 kg=7.983 mg0.1\ \text{mg/kg}
\times 79.832\ \text{kg} = 7.983\
\text{mg}0.1 mg/kg×79.832 kg=7.983 mg.
3. mL required: 7.983 mg×1 mL2 mg=3.9916 mL7.983\
\text{mg} \times \frac{1\ \text{mL}}{2\ \text{mg}} =
3.9916\ \text{mL}7.983 mg×2 mg1 mL=3.9916 mL.
4. Round per facility: morphine can be rounded to the tenth
→ 4.0 mL.
Rationale: Correct dimensional-analysis conversion yields ≈3.99
mL → 4.0 mL. Option A (1.5 mL) would underdose; C (8.0 mL)
overdoses; D (0.8 mL) misplaces decimal.


3)
A child weighs 28 kg. Order: acetaminophen 15 mg/kg PO. The
concentration on the bottle: 160 mg/5 mL. How many mL will
you give?
A. 6.5 mL
B. 13.1 mL
C. 21.0 mL
D. 3.9 mL
Correct answer: B. 13.1 mL

, Solution:
1. Dose mg: 15 mg/kg×28 kg=420 mg15\ \text{mg/kg} \times
28\ \text{kg} = 420\ \text{mg}15 mg/kg×28 kg=420 mg.
2. Concentration: 160 mg/5 mL=32 mg/mL160\ \text{mg} /
5\ \text{mL} = 32\ \text{mg/mL}160 mg/5 mL=32 mg/mL.
3. Volume: 420 mg×1 mL32 mg=13.125 mL420\ \text{mg}
\times \frac{1\ \text{mL}}{32\ \text{mg}} = 13.125\
\text{mL}420 mg×32 mg1 mL=13.125 mL.
4. Round to the nearest 0.1 mL for oral syringe → 13.1 mL.
Rationale: Correct conversion yields 13.125 mL → 13.1 mL.
Options A, C, D are arithmetic errors.


4)
Order: enoxaparin 1 mg/kg subcutaneously for a patient
weighing 80 kg. The available syringe is 100 mg/mL. How many
mL do you administer?
A. 0.08 mL
B. 1.0 mL
C. 0.80 mL
D. 8.0 mL
Correct answer: C. 0.80 mL
Solution:
Dose mg: 1 mg/kg×80 kg=80 mg1\ \text{mg/kg} \times 80\