# Ch 12: Praxis Middle School Math: Ratios & Rate of Change

### About This Chapter

## Praxis Middle School Math: Ratios & Rate of Change - Chapter Summary

In this chapter, our expert instructors will help you improve your ability to solve problems involving ratios, proportions, rate of change, scale factors and percentages. In each short, engaging lesson video, these instructors will present and solve example problems for your benefit. After you've watched these lessons, you should be prepared for questions on the Praxis Middle School Mathematics exam that highlight:

- The relationship between ratios and proportions
- The process of solving proportions problems
- Average rate of change
- Uses of proportions when making scale models
- Applications of scale factors
- The interpretation of scale drawings
- Percentage problems
- Calculations for taxes and discounts

These videos are mobile device-compatible. For a more portable and versatile way to study the lessons, you may watch them on any of your Internet-ready technology. After you've viewed a lesson video, read its transcript for a written overview of the material that will help you reinforce your retention of the information. If you develop a question during this chapter, be sure to ask our instructors for assistance via the lessons' teacher tabs.

### 1. Ratios and Proportions: Definition and Examples

Watch this video lesson to learn how ratios and proportions are related. Also, learn how ratios and proportions are used in real life and how you can apply them to yours.

### 2. Solving Problems Involving Proportions: Definition and Examples

Learn how you can use proportions to find missing sides and how to increase or decrease the sizes of objects to create models of them in this video lesson.

### 3. Average Rate of Change: Definition, Formula & Examples

Average rate of change and slope of a line are very interconnected. They are actually one in the same. In this lesson, we will be discovering how they are interconnected.

### 4. Applying Scale Factors to Perimeter, Area, and Volume of Similar Figures

How do shapes change sizes yet retain their proportions and similarities to other shapes? In this lesson, we'll look at what a scale factor is and how to apply it. We'll consider scale factors with regards to three different aspects of similar shapes: perimeter, area and volume.

### 5. How to Read and Interpret Scale Drawings

Watch this video lesson to learn how scale drawings and legends are used on maps and blueprints. Learn skills that will serve you well when traveling and when looking at the blueprints of a car.

### 6. Percents: Definition, Application & Examples

Maybe you know that 95% is an A and 75% is a C. But what do those percents really mean? In this lesson, we'll learn about percents, including how to convert them to fractions and decimals.

### 7. Taxes & Discounts: Calculations & Examples

When you go shopping, you don't want to be surprised by the amount of tax on an item. You also want to fully understand discounts to know how much you can save. In this lesson, we'll practice calculating both tax and discounts.

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### Other Chapters

Other chapters within the Praxis Middle School Mathematics (5169): Practice & Study Guide course

- Praxis Middle School Math: Number Basics
- Praxis Middle School Math: Rational Numbers
- Praxis Middle School Math: Properties of Numbers
- Praxis Middle School Math: Number Structure
- Praxis Middle School Math: Absolute Value
- Praxis Middle School Math: Equality
- Praxis Middle School Math: Arithmetic Operations
- Praxis Middle School Math: Introduction to Fractions
- Praxis Middle School Math: Operations with Fractions
- Praxis Middle School Math: Decimals
- Praxis Middle School Math: Percents
- Praxis Middle School Math: Proportional Relationships
- Praxis Middle School Math: Estimation
- Praxis Middle School Math: Scientific Notation & Exponents
- Praxis Middle School Math: Square Roots
- Praxis Middle School Math: Roots & Radicals
- Praxis Middle School Math: Algebra Basics
- Praxis Middle School Math: Principles of Algebra
- Praxis Middle School Math: Solving Word Problems
- Praxis Middle School Math: Functions
- Praxis Middle School Math: Linear Equations
- Praxis Middle School Math: Solving Linear Equations
- Praxis Middle School Math: Patterns in Math
- Praxis Middle School Math: Graphing Functions
- Praxis Middle School Math: Polynomials
- Praxis Middle School Math: Quadratic Equations
- Praxis Middle School Math: Systems of Equations
- Praxis Middle School Math: Area, Perimeter & Volume
- Praxis Middle School Math: Properties & Theorems
- Praxis Middle School Math: Parallel, Perpendicular & Intersecting Lines
- Praxis Middle School Math: Properties of Triangles
- Praxis Middle School Math: Similarity & Congruence
- Praxis Middle School Math: Quadrilaterals
- Praxis Middle School Math: Polygons
- Praxis Middle School Math: Circles
- Praxis Middle School Math: Coordinate Geometry
- Praxis Middle School Math: Measurement
- Praxis Middle School Math: Geometric Construction
- Praxis Middle School Math: Data
- Praxis Middle School Math: Line Graphs
- Praxis Middle School Math: Data Presentation
- Praxis Middle School Math: Probability
- Praxis Middle School Math: Counting Principles
- Praxis Middle School Math: Data Sets
- Praxis Middle School Math: Logic
- Praxis Middle School Math: Modeling
- Praxis Middle School Mathematics Flashcards