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.