Calculation of Drug Dosages 12th Edition | Nursing Dosage Calculations Practice Questions, Answers & Rationales

CALCULATION OF DRUG DOSAGES: A WORK TEXT
12TH EDITION
AUTHOR(S)SHEILA J. OGDEN; LINDA FLUHARTY


CHAPTER 1: FRACTIONS — PRETEST

CALCULATION OF DRUG DOSAGES — 12TH EDITION

20 ORIGINAL DOSAGE-CALCULATION PRACTICE QUESTIONS



QUESTION 1

Category: [Basic Mathematics]
Difficulty: Foundational

Question:

A nursing student is reviewing the fraction ( \frac{3}{8} ). Which statement correctly
identifies the numerator and denominator?

A. 3 is the denominator and 8 is the numerator.
B. 3 is the numerator and 8 is the denominator.
C. Both 3 and 8 are denominators.
D. Both 3 and 8 are numerators.

Correct Answer: B. 3 is the numerator and 8 is the denominator.

Calculation / Reasoning:

In a fraction:

[
\frac{\text{numerator}}{\text{denominator}}
]

Therefore:

• Numerator = 3

• Denominator = 8


1

,Rationale:

The numerator represents the number of selected or counted parts, while the
denominator represents the total number of equal parts into which the whole has been
divided. Recognizing these two components is fundamental to performing fraction
calculations used later in dosage mathematics.

Why the other options are incorrect:

A. Reverses the numerator and denominator.
B. Correctly identifies 3 as the numerator and 8 as the denominator.
C. Only 8 is the denominator.
D. Only 3 is the numerator.

Clinical Focus: Correctly identifying numerator and denominator is foundational to
accurate fraction and dosage calculations.



QUESTION 2

Category: [Conversions]
Difficulty: Foundational

Question:

Which fraction is equivalent to ( \frac{1}{2} )?

A. ( \frac{2}{3} )
B. ( \frac{2}{4} )
C. ( \frac{3}{5} )
D. ( \frac{4}{6} )

Correct Answer: B. ( \frac{2}{4} )

Calculation / Reasoning:

Multiply both numerator and denominator of ( \frac{1}{2} ) by 2:

[
\frac{1\times2}{2\times2}=\frac{2}{4}
]

Therefore:

[
\frac{1}{2}=\frac{2}{4}
]
2

,Rationale:

Equivalent fractions have the same numerical value even though they contain different
numbers. Multiplying both the numerator and denominator by the same nonzero
number creates an equivalent fraction. This skill is important when comparing or
manipulating fractions.

Why the other options are incorrect:

A. (2/3) does not have the same value as (1/2).
B. (2/4) simplifies to (1/2), so it is equivalent.
C. (3/5) equals 0.6, not 0.5.
D. (4/6) simplifies to (2/3), not (1/2).

Clinical Focus: Equivalent fractions preserve value and are useful when adjusting a
calculation to a common denominator.



QUESTION 3

Category: [Conversions]
Difficulty: Foundational

Question:

Which fraction is already in its simplest form?

A. ( \frac{6}{8} )
B. ( \frac{9}{12} )
C. ( \frac{5}{7} )
D. ( \frac{10}{15} )

Correct Answer: C. ( \frac{5}{7} )

Calculation / Reasoning:

A fraction is in simplest form when the numerator and denominator have no common
factor other than 1.

• (6/8 = 3/4)

• (9/12 = 3/4)

• (5/7) cannot be reduced

• (10/15 = 2/3)


3

, Therefore, (5/7) is already in simplest form.

Rationale:

Reducing fractions prevents unnecessary complexity and makes calculations easier to
interpret. A fraction is simplified by dividing both numerator and denominator by their
greatest common factor.

Why the other options are incorrect:

A. Both numbers are divisible by 2.
B. Both numbers are divisible by 3.
C. 5 and 7 have no common factor other than 1.
D. Both numbers are divisible by 5.

Clinical Focus: Simplifying fractions reduces calculation complexity and helps prevent
mathematical errors.



QUESTION 4

Category: [Basic Mathematics]
Difficulty: Foundational

Question:

Reduce ( \frac{12}{18} ) to its simplest form.

A. ( \frac{2}{3} )
B. ( \frac{3}{4} )
C. ( \frac{4}{5} )
D. ( \frac{6}{9} )

Correct Answer: A. ( \frac{2}{3} )

Calculation / Reasoning:

The greatest common factor of 12 and 18 is 6.

[
\frac{12\div6}{18\div6}=\frac{2}{3}
]

Rationale:




4