DOSAGE CALCULATIONS MADE
EASY
SOLVING PROBLEMS USING
DIMENSIONAL ANALYSIS
8TH EDITION
• AUTHOR(S)GLORIA PEARL
CRAIG
TEST BANK
,Question 1
Easy
The healthcare provider orders metoprolol tartrate 25 mg by
mouth twice daily. The medication is available in 50 mg scored
tablets. How many tablets will the nurse administer per dose?
A. 0.25 tablet
B. 0.5 tablet
C. 1 tablet
D. 2 tablets
Correct Answer: B. 0.5 tablet
Rationale:
Step 1: Identify the desired dose and the available dose.
Desired: 25 mg
Available: 50 mg/tablet
Step 2: Set up dimensional analysis to cancel units and solve for
tablets.
1 tablet50 mg×25 mg=? tablets50 mg1 tablet×25 mg=? tablets
Step 3: Perform the calculation.
1 tablet×2550=2550=0.5 tablets501 tablet×25=5025=0.5 tablets
Medication Safety Note: Scored tablets can be safely split.
However, if the tablet were not scored, this would be a different
calculation requiring a different available strength. Always verify
,that tablets are scored before splitting to ensure an accurate
dose.
Question 2
Easy
A nurse needs to administer 0.5 L of normal saline over 4 hours.
The drop factor of the available tubing is 15 gtt/mL. Calculate
the flow rate in gtt/min. (Round to the nearest whole number).
A. 21 gtt/min
B. 31 gtt/min
C. 125 gtt/min
D. 7,500 gtt/min
Correct Answer: B. 31 gtt/min
Rationale:
Step 1: Identify conversion factors and the desired units.
Volume: 0.5 L
Time: 4 hours
Drop factor: 15 gtt/mL
Known: 1 L = 1000 mL, 1 hour = 60 minutes
Goal: gtt/min
Step 2: Set up the equation using dimensional analysis to cancel
units.
, 15 gtt1 mL×1000 mL1 L×0.5 L4 hours×1 hour60 minutes=? gtt/
min1 mL15 gtt×1 L1000 mL×4 hours0.5 L×60 minutes1 hour
=? gtt/min
Step 3: Perform the calculation.
15×1000×0.54×60=7500240=31.254×6015×1000×0.5=2407500
=31.25
Round to the nearest whole number: 31 gtt/min.
Medication Safety Note: Always double-check that the final
units match the desired units (gtt/min). This step prevents
errors in IV infusion settings.
Question 3
Easy
The prescriber orders diphenhydramine 37.5 mg IM for an
allergic reaction. The vial is labeled 50 mg/mL. How many mL
will the nurse prepare?
A. 0.55 mL
B. 0.75 mL
C. 1.33 mL
D. 13.3 mL
Correct Answer: B. 0.75 mL
EASY
SOLVING PROBLEMS USING
DIMENSIONAL ANALYSIS
8TH EDITION
• AUTHOR(S)GLORIA PEARL
CRAIG
TEST BANK
,Question 1
Easy
The healthcare provider orders metoprolol tartrate 25 mg by
mouth twice daily. The medication is available in 50 mg scored
tablets. How many tablets will the nurse administer per dose?
A. 0.25 tablet
B. 0.5 tablet
C. 1 tablet
D. 2 tablets
Correct Answer: B. 0.5 tablet
Rationale:
Step 1: Identify the desired dose and the available dose.
Desired: 25 mg
Available: 50 mg/tablet
Step 2: Set up dimensional analysis to cancel units and solve for
tablets.
1 tablet50 mg×25 mg=? tablets50 mg1 tablet×25 mg=? tablets
Step 3: Perform the calculation.
1 tablet×2550=2550=0.5 tablets501 tablet×25=5025=0.5 tablets
Medication Safety Note: Scored tablets can be safely split.
However, if the tablet were not scored, this would be a different
calculation requiring a different available strength. Always verify
,that tablets are scored before splitting to ensure an accurate
dose.
Question 2
Easy
A nurse needs to administer 0.5 L of normal saline over 4 hours.
The drop factor of the available tubing is 15 gtt/mL. Calculate
the flow rate in gtt/min. (Round to the nearest whole number).
A. 21 gtt/min
B. 31 gtt/min
C. 125 gtt/min
D. 7,500 gtt/min
Correct Answer: B. 31 gtt/min
Rationale:
Step 1: Identify conversion factors and the desired units.
Volume: 0.5 L
Time: 4 hours
Drop factor: 15 gtt/mL
Known: 1 L = 1000 mL, 1 hour = 60 minutes
Goal: gtt/min
Step 2: Set up the equation using dimensional analysis to cancel
units.
, 15 gtt1 mL×1000 mL1 L×0.5 L4 hours×1 hour60 minutes=? gtt/
min1 mL15 gtt×1 L1000 mL×4 hours0.5 L×60 minutes1 hour
=? gtt/min
Step 3: Perform the calculation.
15×1000×0.54×60=7500240=31.254×6015×1000×0.5=2407500
=31.25
Round to the nearest whole number: 31 gtt/min.
Medication Safety Note: Always double-check that the final
units match the desired units (gtt/min). This step prevents
errors in IV infusion settings.
Question 3
Easy
The prescriber orders diphenhydramine 37.5 mg IM for an
allergic reaction. The vial is labeled 50 mg/mL. How many mL
will the nurse prepare?
A. 0.55 mL
B. 0.75 mL
C. 1.33 mL
D. 13.3 mL
Correct Answer: B. 0.75 mL
