# 6: Ratio and Proportion

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• 6.1: Ratio and Proportion
Examples and applications of ratios are limitless: speed is a ratio that compares changes in distance with respect to time, acceleration is a ratio that compares changes in speed with respect to time, and percentages compare the part with the whole. We’ve already studied one classic ratio, the ratio of the circumference of a circle to its diameter, which gives us the definition of π.
• 6.2: Introduction to Ratios and Rates
We use ratios to compare two numeric quantities or quantities with the same units.
• 6.3: Introduction to Proportion
In this section, we equate ratio and rates in a construct called a proportion.
• 6.4: Unit Conversion - American System
In this section we will develop a technique for converting units used in the American system. We begin with a discussion of common measurements of length in the United States.
• 6.5: Unit Conversion- Metric System
The metric system of units is the standard system of units preferred by scientists. It is based on the base ten number system and its decimal format is more friendly to users of this system. There is a common set of prefixes adopted by the metric system to indicate a power of ten to apply to the base unit.
• 6.6: American Units to Metric Units and Vice-Versa
We often need to convert from the American system of units to the metric system of units or vice-versa (imagine traveling to a European country using the metric system). That will be our focus in this section.

This page titled 6: Ratio and Proportion is shared under a CC BY-NC-SA 3.0 license and was authored, remixed, and/or curated by David Arnold.