Proportion

In mathematics, a proportion is an equation that states that two ratios are equal. It can be written in the form a/b = c/d, where a, b, c, and d are numbers and b and d are not zero. Proportions are used to compare the relative sizes of different quantities. When two ratios are equal, they form a proportion.

Study Guide

Example 1:

Find the missing number in the proportion: 3/5 = x/15

Solution:

Using the property of proportions, we can cross multiply to solve for the missing number. This means we multiply the extremes (3 * 15) and the means (5 * x), and then set the two products equal to each other:

Example 2:

If 4/7 = 12/y, find the value of y.

Solution:

Again, we can use the property of proportions to solve for the missing number. We cross multiply the extremes (4 * y) and the means (7 * 12), and then set the two products equal to each other:

Practice Problems:

1. If 2/3 = x/9, find the value of x.
2. If 5/8 = 25/y, find the value of y.
3. If 9/12 = 15/x, find the value of x.

Once you've completed the practice problems, you can check your answers below:

Answers:

1. x = 6
2. y = 40
3. x = 20