# Lesson 3.6: Ratios and Proportions A ratio is a comparison of two

```Lesson 3.6: Ratios and Proportions
A ratio is a comparison of two numbers by division. The ratio of x to y can be
expressed the following ways-&gt;
x to y
𝑥
𝑦
x:y
An equation stating that two ratios are equal is called a proportion.
Determine Whether Ratios Form a Proportion
7
49
𝑎𝑛𝑑 56
8
Method 1: Reduce both fractions
Method 2: Use cross products
means-extremes property In any proportion, the product of the means equals the product of
the extremes. Some people learn this as &quot;cross products are equal in any proportion.&quot;
means In the proportion a/b = c/d, the
numbers b and c.
extremes In the proportion
a/b= c/d, the numbers a
and d.
Further Examples:
Determine whether each pair of ratios forms a proportion:
.25 1.25
, 2
.6
4 16
,
5 20
Solving Proportions
𝑛
3
=
12 8
The gear on a bicycle is 8:5. This means that for every 8 turns of the pedals, the
wheel turns 5 times. Suppose the bicycle wheel turns about 2435 times during a
trip. How many times would you have to turn the pedals during the trip?
In a road atlas, the scale for the map of Connecticut is 5 inches = 41 miles. The
scale for the map of Texas is 5 inches = 44 miles. What are the distances
represented by 2 &frac12; inches on each map?
Homework: pages 158-15912-34 EVEN
```