PROPORTION
Definition Of Proportion
A proportion is an equation written in the form 
stating that two ratios are equivalent.
In other words, two sets of numbers are proportional if one set is a constant times the other.
Video Examples: What is a Proportion?
Example of Proportion
, 
are examples of proportions.
Solved Example on Proportion
Ques: A cardboard model of a Honda bike is part of an outdoor display. Its height is 4 ft. The actual Honda bike is 5 ft long and 2 ft high. Find the length of the model, if its dimensions are proportionate to the real bike.
Choices:
A. 11 ft
B. 12 ft
C. 9 ft
D. 10 ft
Correct Answer: D
Solution:
Step 1: Let n be the length of Honda bike cardboard model.
Step 2: 
[Write a proportion.]
Step 3: n × 2 = 4 × 5 [Write the cross products.]
Step 4: n = 10 [Simplify the expression.]
Step 5: The length of the Honda bike cardboard model is 10 ft.
Quick Summary
- Proportions compare two ratios.
- Cross-multiplication can be used to solve proportions.
- Proportions are used to solve real-world problems involving scaling and relationships between quantities.
🍎 Teacher Insights
Use visual aids like diagrams and manipulatives to help students understand the concept of equivalent ratios. Emphasize the importance of units when setting up proportions. Encourage students to check their work by verifying that the cross products are equal.🎓 Prerequisites
- Understanding of ratios
- Basic algebra
- Fractions
Check Your Knowledge
Q1: Solve for x: \frac{2}{3} = \frac{x}{9}
Q2: Which proportion is correctly set up to solve the following problem: If 3 apples cost $2, how much do 9 apples cost?
Frequently Asked Questions
Q: How do I know if two ratios form a proportion?
A: If their cross products are equal, the ratios form a proportion.
Q: Where can I use proportions in real life?
A: Proportions are used in cooking (scaling recipes), map reading (determining distances), and calculating unit prices.