RN FUNDAMENTALS DOSAGE
CALCULATION EXAM 2024
A nurse is preparing to administer phenytoin 100 mg PO every 8 hours. Available is
phenytoin suspension 125 mg/5 mL. How many mL should the nurse administer per
dose?
(Round to nearest whole number. Use a leading zero if it applies. Do not use a trailing
zero.) --ANSWER: Answer: 4 mL
Follow these steps for the Ratio and Proportion method of calculation:
Step 1: What is the unit of measurement the nurse should calculate? mL
Step 2: What is the dose the nurse should administer? Dose to administer = Desired
100 mg
Step 3: What is the dose available? Dose available = Have 125 mg
Step 4: Should the nurse convert the units of measurement? No
Step 5: What is the quantity of the dose available? 5 mL
Step 6: Set up an equation and solve for X.
Have/Quantity = Desired/X
125 mg/ 5 mL = 100 mg/X mL
X mL = 4 mL
Step 7: Round if necessary.
Step 8: Determine whether the amount to administer makes sense. If there are 125
mg/5 mL and the prescription reads 100 mg, it makes sense to administer 4 mL. The
nurse should administer phenytoin 4 mL PO every 8 hr.
A nurse is preparing to administer phenobarbital 6mg/kg/day PO divided in equal
doses every 12 hours to a patient who weighs 44 lb. Available is phenobarbital elixir
20 mg/5 mL. The nurse should administer how many mL per dose?
(Round to nearest whole number. Use a leading zero if it applies. Do not use a trailing
zero.) --ANSWER: Answer: 15 mL
Follow these steps for the Ratio and Proportion method of calculation:
Step 1: What is the unit of measurement the nurse should calculate? kg
Step 2: Set up an equation and solve for X.
2.2 lb/ 1 kg = Client's weight in lb/X kg
2.2 lb/ 1 kg = 44 lb/ X kg
X kg = 20 kg
Step 3: What is the unit of measurement the nurse should calculate? mg
Step 4: Set up an equation and solve for X.
X = Dose per kg × Client's weight in kg
X mg = 6 mg/kg × 20 kg
X mg = 120 mg
The dose is divided equally every 12 hours; therefore, divide X by 2.
120 mg = 60 mg2
Step 5: What is the unit of measurement the nurse should calculate? mL
, Step 6: What is the dose the nurse should administer? Dose to administer = Desired
60 mg
Step 7: What is the dose available? Dose available = Have 20 mg
Step 8: Should the nurse convert the units of measurement? No
Step 9: What is the quantity of the dose available? 5 mL
Step 10: Set up an equation and solve for X.
Have/Quantity = Desired/X
20 mg/ 5 mL = 60 mg/ X mL
X mL = 15 mL
Step 11: Round if necessary.
Step 12: Determine whether the amount to administer makes sense. If there are 20
mg/5 mL and the prescription reads 6 mg/kg/day, it makes sense to administer 15 mL.
The nurse should administer phenobarbital elixir 15 mL PO every 12 hr.
A nurse is preparing to administer 2 Tbsp of ibuprofen to a client. How many mL
should the nurse administer per dose?
(Round to the nearest whole number. Use a leading zero if it applies. Do not use a
trailing zero.) --ANSWER: Answer: 30 mL
Follow these steps for the Ratio and Proportion method of calculation:
Step 1: What is the unit of measurement the nurse should calculate? mL
Step 2: What is the dose the nurse should administer? Dose to administer = Desired 2
Tbsp
Step 3: What is the dose available? Dose available = Have 1 mL
Step 4: Should the nurse convert the units of measurement? Yes (Tbsp does not equal
mL)
1 Tbsp / 15 mL = 2 Tbsp / X mL
X mL = 30 mL
Step 5: Round if necessary.
Step 6: Determine whether the amount to administer makes sense. If the prescription
reads 2 Tbsp and 1 Tbsp equals 15 mL, it makes sense to administer 30 mL. The
nurse should administer ibuprofen 30 mL.
A nurse is preparing to administer prednisone 50 mg PO to a patient. Available is
prednisone 20 mg/tablet. How many tablets should the nurse administer?
(Round answer to nearest tenth. Use a leading zero if it applies. Do not use a trailing
zero.) --ANSWER: Answer: tablets
Follow these steps for the Ratio and Proportion method of calculation:
Step 1: What is the unit of measurement the nurse should calculate? tablet(s)
Step 2: What is the dose the nurse should administer? Dose to administer = Desired
50 mg
Step 3: What is the dose available? Dose available = Have 20 mg
Step 4: Should the nurse convert the units of measurement? No
Step 5: What is the quantity of the dose available? 1 tablet
Step 6: Set up an equation and solve for X.
Have/Quantity = Desired/X
20 mg/ 1 tablet = 50 mg / X tablet(s)
CALCULATION EXAM 2024
A nurse is preparing to administer phenytoin 100 mg PO every 8 hours. Available is
phenytoin suspension 125 mg/5 mL. How many mL should the nurse administer per
dose?
(Round to nearest whole number. Use a leading zero if it applies. Do not use a trailing
zero.) --ANSWER: Answer: 4 mL
Follow these steps for the Ratio and Proportion method of calculation:
Step 1: What is the unit of measurement the nurse should calculate? mL
Step 2: What is the dose the nurse should administer? Dose to administer = Desired
100 mg
Step 3: What is the dose available? Dose available = Have 125 mg
Step 4: Should the nurse convert the units of measurement? No
Step 5: What is the quantity of the dose available? 5 mL
Step 6: Set up an equation and solve for X.
Have/Quantity = Desired/X
125 mg/ 5 mL = 100 mg/X mL
X mL = 4 mL
Step 7: Round if necessary.
Step 8: Determine whether the amount to administer makes sense. If there are 125
mg/5 mL and the prescription reads 100 mg, it makes sense to administer 4 mL. The
nurse should administer phenytoin 4 mL PO every 8 hr.
A nurse is preparing to administer phenobarbital 6mg/kg/day PO divided in equal
doses every 12 hours to a patient who weighs 44 lb. Available is phenobarbital elixir
20 mg/5 mL. The nurse should administer how many mL per dose?
(Round to nearest whole number. Use a leading zero if it applies. Do not use a trailing
zero.) --ANSWER: Answer: 15 mL
Follow these steps for the Ratio and Proportion method of calculation:
Step 1: What is the unit of measurement the nurse should calculate? kg
Step 2: Set up an equation and solve for X.
2.2 lb/ 1 kg = Client's weight in lb/X kg
2.2 lb/ 1 kg = 44 lb/ X kg
X kg = 20 kg
Step 3: What is the unit of measurement the nurse should calculate? mg
Step 4: Set up an equation and solve for X.
X = Dose per kg × Client's weight in kg
X mg = 6 mg/kg × 20 kg
X mg = 120 mg
The dose is divided equally every 12 hours; therefore, divide X by 2.
120 mg = 60 mg2
Step 5: What is the unit of measurement the nurse should calculate? mL
, Step 6: What is the dose the nurse should administer? Dose to administer = Desired
60 mg
Step 7: What is the dose available? Dose available = Have 20 mg
Step 8: Should the nurse convert the units of measurement? No
Step 9: What is the quantity of the dose available? 5 mL
Step 10: Set up an equation and solve for X.
Have/Quantity = Desired/X
20 mg/ 5 mL = 60 mg/ X mL
X mL = 15 mL
Step 11: Round if necessary.
Step 12: Determine whether the amount to administer makes sense. If there are 20
mg/5 mL and the prescription reads 6 mg/kg/day, it makes sense to administer 15 mL.
The nurse should administer phenobarbital elixir 15 mL PO every 12 hr.
A nurse is preparing to administer 2 Tbsp of ibuprofen to a client. How many mL
should the nurse administer per dose?
(Round to the nearest whole number. Use a leading zero if it applies. Do not use a
trailing zero.) --ANSWER: Answer: 30 mL
Follow these steps for the Ratio and Proportion method of calculation:
Step 1: What is the unit of measurement the nurse should calculate? mL
Step 2: What is the dose the nurse should administer? Dose to administer = Desired 2
Tbsp
Step 3: What is the dose available? Dose available = Have 1 mL
Step 4: Should the nurse convert the units of measurement? Yes (Tbsp does not equal
mL)
1 Tbsp / 15 mL = 2 Tbsp / X mL
X mL = 30 mL
Step 5: Round if necessary.
Step 6: Determine whether the amount to administer makes sense. If the prescription
reads 2 Tbsp and 1 Tbsp equals 15 mL, it makes sense to administer 30 mL. The
nurse should administer ibuprofen 30 mL.
A nurse is preparing to administer prednisone 50 mg PO to a patient. Available is
prednisone 20 mg/tablet. How many tablets should the nurse administer?
(Round answer to nearest tenth. Use a leading zero if it applies. Do not use a trailing
zero.) --ANSWER: Answer: tablets
Follow these steps for the Ratio and Proportion method of calculation:
Step 1: What is the unit of measurement the nurse should calculate? tablet(s)
Step 2: What is the dose the nurse should administer? Dose to administer = Desired
50 mg
Step 3: What is the dose available? Dose available = Have 20 mg
Step 4: Should the nurse convert the units of measurement? No
Step 5: What is the quantity of the dose available? 1 tablet
Step 6: Set up an equation and solve for X.
Have/Quantity = Desired/X
20 mg/ 1 tablet = 50 mg / X tablet(s)
