Unit 3/ Module 5: RATIOToday we will learn about….. Ra-T-o??

-OR-

Ra-sh-o??

Lets do a comparison within our class…. Compare the number of boys to

girls in THIS class.

The number of boys =

The number of girls =

If we compare boys to girls we get

9 boys to 11 girls.

9 boys to 11 girls.

This comparison (ratio) can be written three different ways…

Part to part--- 9 to 11 9: 11 9/11 or Part to whole---- 9 out of 20

Basically a RATIO is a comparison of two (or more) quantitiesto establish a relationship between them.

When/where do we see ratios used in our everyday life?

Consumer data…

9:10 dentist recommend

When writing a ratio, ORDER does matter.

Cooking/Recipes

A recipe for cookies uses 3 cups of flour and 2 cups of milk---- 3:2

What would the cookies taste like

if you if you followed the ratio of 2:3 instead??????

Driving

Mr. Benny drove 135 miles in 3 hrs 135:3

Use of ratio in school….

class-size 22:1

love school lunch 7:10

Johnny raises his hand 9:10

What is a ratio?

A relationship between two numbers of the same kind

When writing a ratio, ORDER does matter

HERE WE ARE COMPARING FRUIT…6 ORANGES TO 7 APPLES…… 6:77 APPLES TO 6 ORANGES…… 7:6

YOU MUST WRITE THE RATIO EXACTLY AS IT WILL BE ASKED.

It’s Friday night and your friends are having a party…… The ratio of girls to guys is 2 to 12.

Would you want to attend the party?

How many basketballs to footballs are there?

For every 4 basketballs there are 6 footballs.

The ratio is 4 to 6.

What are some other ways we can write the ratio of basketball to footballs?

4 to 6

4 : 6

4 6

First quantity to Second quantity

First quantity : Second quantity

First quantity divided by the second quantity (as a fraction).

Every ratio can be written in 3 ways:

Careful!!

Order matters in a ratio.

4 to 6

Is NOT the same as

6 to 4

Equivalent Ratios can be formed by multiplying the ratio by any number.

For example, the ratio 2 : 3 can also be written as 4 : 6 (multiply original ratio by by 2) 6 : 9 (multiply original ratio by by 3) 8 : 12 (multiply original ratio by by 4)

The ratio 2 : 3 can be expressed as 2x to 3x (multiply the original ratio by any SAME number x)

A bag contains 18 yellow, blue, and red marbles. The ratio of yellow to blue to

red marbles is 4 : 2 : 3. 1) Write the ratio of yellow to blue marbles in simplest form.2) What is the ratio of yellow to red marbles?3) How many yellow marbles are there?

You can compare ratios part to part part to part as show above OR part to wholepart to whole.Ex. How many red marbles to the whole (or total) amount of marbles?

Lets do some group practice.

Quick review of group expectation…*respect your group member… take turns & listen more than you speak * No chiefs… everyone’s an Indian! No bossy take-over behaviors.* Speak at a volume that your group (not entire class) can hear you.