Download Ratios

Ratios
We are going to
• Write ratios as fractions (in simplest form)
• Find Unit Rates
Ratio Example
We are going to mix paint to get the correct shade.
I am going to mix 2 parts sky blue and 4 parts green
I can write this ratio 3 ways
A ratio is a comparison
of two numbers using
division.
2 to 4
2:4
2/4
So we can reduce this ratio to 1 to 2, 1:2 or 1/2
Another Example
I went fishing and caught 12 bass. Of these bass, 8 were brown bass.
What was the ratio of brown bass to total bass caught (in simplest
form)?
The ratio is 8 small mouth to the total of 12 bass
8 2

12 3
For every 3 bass caught, 2 were brown bass
Compare Footballs to Baseballs
Write a ratio that compares the number of footballs to the number of
baseballs.
footballs
4
2

6
3
baseballs
2 to 3, or 2:3
Compare Part To Whole
Write a ratio that compares the number of cupcakes to the
total number of snacks.
cupcakes
snacks
1
4

3
12
Or 1 of 3 or 1:3
Unit Rates
A rate is a ratio of two measurements having different kinds of units
100 miles in 5 seconds
$5 for 2 pounds
When a rate is simplified such that the denominator is 1, it is
called a unit rate.
Calculating Unit Rate
Given a ratio as a fraction, divide the numerator by the denominator
to get a decimal answer.
MUST give the units for a unit rate!
$17 for 5 CDs
34 miles in 2.8 hours
Divide $17.00 by 5
You will get $3.40 for 1 CD
34  2.8  12.1 miles per hour (mph)
18 homework assignments in 3 weeks
Your Turn
Express each ratio in simplest form
1. 4 goals in 10 shot attempts
2. 15 dimes out of 25 coins
Express each ratio as a unit rate (MUST have units on answer)
1. $24 for 4 concert tickets
3. 100 feet in 10 seconds
2. 12 inches of snow in 6 hours
4. 50 miles on 2 gallons
Homework
Homework page 371 #3 through 18 evens
We will do #3 together – these are the ratio
problems
Copy exactly as on overhead
The unit rate problems are on:
page 376 #10 through 24 evens.
We will do #5 together as an example.
Remember to show your work include unit
measurement such as per inch.