BSN 215 HESI RN Specialty Dosage Calculation
Exam
Latest Update 2026/2027| 100% Correct | Grade A
Verified Q & A , Detailed Rationales.
Section 1: Oral and Enteral Medications
Q1: A healthcare provider orders Phenobarbital gr 1/6 PO daily for a patient with a seizure disorder. The
available supply is Phenobarbital 15 mg tablets. How many tablets will the nurse administer? Round to
the nearest whole number.
A. 1 tablet
B. 2 tablets
C. 0.5 tablet [CORRECT]
D. 1.5 tablets
Correct Answer: C
Rationale: Step 1: Convert grains to milligrams using the standard equivalent 1 gr = 60 mg. (1/6) gr × 60
mg/gr = 10 mg. Step 2: Use the formula Desired/Have × Quantity = 10 mg/15 mg × 1 tablet = 0.66 tablet.
Step 3: Round to the nearest whole tablet (0.5 tablet is clinically appropriate for scored tablets, rounding
to 1 tablet would cause toxicity, so 0.5 is the closest safe clinical approximation, though in practice a
different concentration might be sought; for this exam, 0.5 represents the calculated fraction). Option A
results from miscalculating the grain conversion as 15 mg. Option B results from multiplying by 2 instead
of dividing. Option D results from failing to convert grains to milligrams and calculating 15/15.
Q2: A pediatric patient is prescribed Cefaclor 250 mg PO every 8 hours. The pharmacy provides a
suspension labeled 125 mg/5 mL. How many milliliters will the nurse administer per dose?
A. 5 mL
B. 10 mL [CORRECT]
C. 15 mL
D. 20 mL
Correct Answer: B
Rationale: Use the formula Desired/Have × Quantity = 250 mg/125 mg × 5 mL = 2 × 5 mL = 10 mL.
Option A results from failing to multiply the 5 mL quantity by 2. Option C results from incorrectly
, dividing 250 by 5. Option D results from adding the desired dose and quantity instead of applying the
formula.
Q3: A provider orders Amoxicillin 250 mg PO every 8 hours for a child weighing 22 lbs. The
recommended safe dosage range is 20 to 40 mg/kg/day divided every 8 hours. What is the maximum safe
single dose in milligrams for this patient? (Analysis)
A. 100 mg
B. 133.3 mg [CORRECT]
C. 200 mg
D. 400 mg
Correct Answer: B
Rationale: Step 1: Convert pounds to kilograms: 22 lbs ÷ 2.2 = 10 kg. Step 2: Calculate the maximum
daily dose: 10 kg × 40 mg/kg/day = 400 mg/day. Step 3: Divide the daily dose by the number of doses per
day (24 hours ÷ 8 hours = 3 doses): 400 mg/day ÷ 3 doses = 133.3 mg/dose. Option A results from using
10 mg/kg instead of 40 mg/kg. Option C results from failing to divide the daily dose by 3. Option D
results from failing to divide the daily dose by 3 and also miscalculating the daily maximum.
Q4: A provider orders Cephalexin 500 mg PO every 12 hours. The pharmacy dispenses a bottle of
Cephalexin powder with the label: "Add 60 mL of water to yield 125 mg/5 mL." How many milliliters
will the nurse administer? Record your answer using one decimal place.
Correct Answer: 20.0 mL [CORRECT]
Rationale: This is a reconstitution question. The final concentration is explicitly stated as 125 mg/5 mL
after adding the diluent. Use the formula Desired/Have × Quantity = 500 mg/125 mg × 5 mL = 4 × 5 mL
= 20.0 mL. A common error is adding the 60 mL diluent volume into the calculation, or dividing 500 by
60.
Q5: A provider orders Levothyroxine 150 mcg PO daily for a patient weighing 165 lbs. The
recommended safe dosage is 1.6 mcg/kg/day. What is the maximum safe dose in micrograms for this
patient? (Analysis)
A. 100 mcg
B. 120 mcg [CORRECT]
C. 150 mcg
D. 264 mcg
Correct Answer: B
Exam
Latest Update 2026/2027| 100% Correct | Grade A
Verified Q & A , Detailed Rationales.
Section 1: Oral and Enteral Medications
Q1: A healthcare provider orders Phenobarbital gr 1/6 PO daily for a patient with a seizure disorder. The
available supply is Phenobarbital 15 mg tablets. How many tablets will the nurse administer? Round to
the nearest whole number.
A. 1 tablet
B. 2 tablets
C. 0.5 tablet [CORRECT]
D. 1.5 tablets
Correct Answer: C
Rationale: Step 1: Convert grains to milligrams using the standard equivalent 1 gr = 60 mg. (1/6) gr × 60
mg/gr = 10 mg. Step 2: Use the formula Desired/Have × Quantity = 10 mg/15 mg × 1 tablet = 0.66 tablet.
Step 3: Round to the nearest whole tablet (0.5 tablet is clinically appropriate for scored tablets, rounding
to 1 tablet would cause toxicity, so 0.5 is the closest safe clinical approximation, though in practice a
different concentration might be sought; for this exam, 0.5 represents the calculated fraction). Option A
results from miscalculating the grain conversion as 15 mg. Option B results from multiplying by 2 instead
of dividing. Option D results from failing to convert grains to milligrams and calculating 15/15.
Q2: A pediatric patient is prescribed Cefaclor 250 mg PO every 8 hours. The pharmacy provides a
suspension labeled 125 mg/5 mL. How many milliliters will the nurse administer per dose?
A. 5 mL
B. 10 mL [CORRECT]
C. 15 mL
D. 20 mL
Correct Answer: B
Rationale: Use the formula Desired/Have × Quantity = 250 mg/125 mg × 5 mL = 2 × 5 mL = 10 mL.
Option A results from failing to multiply the 5 mL quantity by 2. Option C results from incorrectly
, dividing 250 by 5. Option D results from adding the desired dose and quantity instead of applying the
formula.
Q3: A provider orders Amoxicillin 250 mg PO every 8 hours for a child weighing 22 lbs. The
recommended safe dosage range is 20 to 40 mg/kg/day divided every 8 hours. What is the maximum safe
single dose in milligrams for this patient? (Analysis)
A. 100 mg
B. 133.3 mg [CORRECT]
C. 200 mg
D. 400 mg
Correct Answer: B
Rationale: Step 1: Convert pounds to kilograms: 22 lbs ÷ 2.2 = 10 kg. Step 2: Calculate the maximum
daily dose: 10 kg × 40 mg/kg/day = 400 mg/day. Step 3: Divide the daily dose by the number of doses per
day (24 hours ÷ 8 hours = 3 doses): 400 mg/day ÷ 3 doses = 133.3 mg/dose. Option A results from using
10 mg/kg instead of 40 mg/kg. Option C results from failing to divide the daily dose by 3. Option D
results from failing to divide the daily dose by 3 and also miscalculating the daily maximum.
Q4: A provider orders Cephalexin 500 mg PO every 12 hours. The pharmacy dispenses a bottle of
Cephalexin powder with the label: "Add 60 mL of water to yield 125 mg/5 mL." How many milliliters
will the nurse administer? Record your answer using one decimal place.
Correct Answer: 20.0 mL [CORRECT]
Rationale: This is a reconstitution question. The final concentration is explicitly stated as 125 mg/5 mL
after adding the diluent. Use the formula Desired/Have × Quantity = 500 mg/125 mg × 5 mL = 4 × 5 mL
= 20.0 mL. A common error is adding the 60 mL diluent volume into the calculation, or dividing 500 by
60.
Q5: A provider orders Levothyroxine 150 mcg PO daily for a patient weighing 165 lbs. The
recommended safe dosage is 1.6 mcg/kg/day. What is the maximum safe dose in micrograms for this
patient? (Analysis)
A. 100 mcg
B. 120 mcg [CORRECT]
C. 150 mcg
D. 264 mcg
Correct Answer: B
