Solving Problems Using Dimensional

DOSAGE CALCULATIONS MADE
EASY
SOLVING PROBLEMS USING
DIMENSIONAL ANALYSIS
8TH EDITION
• AUTHOR(S)GLORIA PEARL
CRAIG




TEST BANK

,Question 1
The healthcare provider orders amoxicillin 0.5 g PO every 12
hours for a pediatric patient with an ear infection. The
medication is available as a liquid suspension with a
concentration of 250 mg per 5 mL. How many milliliters will the
nurse administer per dose?
A. 2.5 mL
B. 5 mL
C. 10 mL
D. 20 mL
Correct Answer: C
Rationale:
Step 1: Identify the desired dose and the available
concentration. The order is for 0.5 g. The available
concentration is 250 mg/5 mL. First, convert the order to the
same unit as the available medication.
Step 2: Set up the dimensional analysis equation. The goal is to
end with the unit mL. Start with the ordered dose.
0.5 g1×1000 mg1 g×5 mL250 mg=? mL10.5 g×1 g1000 mg
×250 mg5 mL=? mL
Step 3: Cancel the units of "g" and "mg".

,0.5×1000×5250 mL=2500250 mL=10 mL2500.5×1000×5
mL=2502500 mL=10 mL
Medication Safety Note: Always verify that the final dose is
within the safe range for a pediatric patient. Confusing grams
with milligrams is a common and potentially dangerous error.


Question 2
A patient is prescribed 20 mg of furosemide IV push. The
pharmacy sends a vial labeled 40 mg/mL. How many milliliters
will the nurse withdraw for the correct dose?
A. 0.5 mL
B. 1 mL
C. 2 mL
D. 4 mL
Correct Answer: A
Rationale:
Step 1: The desired dose is 20 mg. The available concentration
is 40 mg per 1 mL.
Step 2: Set up the equation to solve for the unknown volume
(X) in mL. In dimensional analysis, we can write:
1 mL40 mg×20 mg1=? mL40 mg1 mL×120 mg=? mL
Step 3: Cancel the unit "mg".

, 1×2040 mL=0.5 mL401×20 mL=0.5 mL
Medication Safety Note: IV push medications require a slow
and careful administration rate. Always double-check the
concentration of high-alert medications like furosemide. "High-
alert" means that a small error in dose can cause significant
patient harm.


Question 3
The nurse is preparing to administer 2.5 mL of a medication.
The available syringes are labeled in teaspoons. The nurse
knows that 1 tsp = 5 mL. How many teaspoons should the
patient receive?
A. 0.25 tsp
B. 0.5 tsp
C. 1 tsp
D. 2.5 tsp
Correct Answer: B
Rationale:
Step 1: The desired dose is 2.5 mL. The conversion factor is 1
tsp = 5 mL.
Step 2: Set up the equation.
2.5 mL1×1 tsp5 mL=? tsp12.5 mL×5 mL1 tsp=? tsp