Module 3 - Ratio and Proportion

Overview

Ratio and proportion form the mathematical backbone of nearly every dosage calculation in nursing. Once you can confidently set up and solve a proportion, most medication calculations become straightforward.

This module builds directly on the conversion and dimensional analysis skills from Module 2.

Learning Objectives

By the end of this module you should be able to:

• Define and write ratios in multiple formats
• Set up and solve proportions
• Use cross-multiplication to find unknown values
• Apply ratio and proportion to clinical dosage problems
• Recognize when an answer is unreasonable

Topics

• Ratios
• Proportions
• Cross Multiplication
• Clinical Applications

Estimated Time

Approximately 1.5-2 hours including practice problems.

Before You Begin

Make sure you are comfortable with fractions and unit conversions from Modules 1 and 2. Every proportion in this module involves fractions — if they feel shaky, do a quick review before continuing.

Connection to Dimensional Analysis

Ratio and proportion and dimensional analysis are two different approaches to the same problems. Some nurses prefer one method, some prefer the other. Learning both gives you flexibility and a way to double-check your work.