AN INTRODUCTION TO RATIOS

A Ratio
Compares two items.
It can be written in three ways.
2:1, 2 to 1, and the most common way is as a fraction in simplest form.
2
--
1

I CAN..

• Write ratio notation in three ways.
• Read and write ratios correctly.
• Simplify ratios.

The ratio of wings to beaks in the bird house at the zoo was 2:1, because for every 2 wings there was 1 beak.
2 to 1
2:1
2/1

WHY?

YOUR TURN

Now count the number of males in the room.

Now count the number of females in the room.

Let's write these statistics down as a comparison between 2 different items.

First: males to total number of students.
Now: females to males.

There is a total of____
Students in the room.
There are ___ males in the room.
There are____ females in the room.

The ratio

3 excepted ways to write a ratio.
First is to compare 2 items using the word to..
Second is to compare using :
The third and most often used is as a fraction. Simplified

Let's look at the handout I gave you called "find the ratio".

Count the number of hearts ____.
Count the number of triangles_____.

Be sure to simplify
By finding the greatest common factor.
Eliminate all factors the two have in common.
Reduce.

IN THE FIRST PROBLEM THE COMMON FACTOR IS 8

Take a look at the diagrams.
Find the number of items down in each visual.
This is the number each item has in common.
Look at the top row on each. This is the simplified answer.

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Order the numbers are originally listed in is important.
You must list the items in the same way.
(The first listed will be listed first.)