1. POD
Find your pulse. We are going to count how many beats your heart makes in 2 minutes. Teacher will keep the time. You keep count.
Write your results as a ratio.

2. 4-1 Ratios
A ratio is a comparison of two quantities by division. You can write a ratio in three ways.
Arithmetic
Algebra
5 to 7
x to y
5 : 7
x : y 5 7 x y

3. 5 to 8 5 : 8 5 8 Write the ratio of black keys to white keys.
Example: I do
Write the ratio of black keys to white keys.
black keys
5 to 8
white keys
black keys
5 : 8
white keys 5 8
black keys
white keys

4. Example: we do
Write the ratio of windows to lights in this classroom in three different ways
Windows
6 to 8
lights
windows
6 : 8
lights 6 8
windows
lights

5. = 4 5 8 10 Ex: I do Find a ratio equivalent to 4/5
Two ratios are equivalent ratios if their corresponding fractions are equivalent
Ex: I do
Find a ratio equivalent to 4/5 4 5 8 10 x2 = x2

6. = = 7 9 14 18 7 9 21 27 Ex: we do Find a ratio equivalent to 7/9 x2 x2or 7 9 21 27 x3 = x3

7. Comparing Ratios
To compare ratios, convert them into decimals or fractions with common denominators.

8. Comparing Ratios I do
An official U.S. flag has a length to width ratio of 19:10. The largest U.S. flag measures 505 ft. by 225 ft. Is this an official U.S. flag?
Largest flag
Official flag
505
255 19 10
≈ 1.98
= 1.9
Since 1.98 is not equal to 1.9, the largest U.S. flag is not an official U.S. flag

9. Comparing Ratios: we do
The ratio of girls to boys enrolled at King Middle School is 15:16. There are 195 girls and 208 boys in grade 8. Is the ratio of girls to boys in grade 8 the same as the ratio for the entire school?
School
8th grade 15 16
195
208 ≈ =
Yes, the ratios of girls to boys in the 8th grade is equivalent to the ratio for the whole school. Both are equal to

10. Whiteboard time!
Write the ratio of chairs to tables in this classroom in three different forms
39 chairs: 9 tables
39 chairs
9 tables
39 chairs to 9 tables

11. Are the following ratios equivalent?
1.) :3
128:54
Not equivalent
2.) to 7
30.5 to 35
Equivalent

12. Let’s try a few on our own.
Pg txtbk #2-32 evens

14. Adrienne biked 24 miles in 4 hours
Adrienne biked 24 miles in 4 hours. If she biked at a constant speed, how many miles did she ride in 1 hour?
24 mi.
4 hrs.
Write it as a fraction
24 ÷ 4
4 ÷ 4
Divide numerator and denominator by 4
6 mi.
1 hr.
Simplify

15. Ex. 2: Find the unit price if it costs $2 for eight juice boxes.
$ 2
8 boxes
Write it as a fraction
2 ÷ 8
8 ÷ 8
Divide the numerator and denominator by 8
$ 0.25
1 box
Simplify
The unit price is $0.25 per box

16. 147 grams 15 servings 9.8 grams 1 serving
A package of cheddar cheese contains 15 servings and has a total of 147 grams of fat. Find the unit rate of grams of fat per serving.
147 grams
15 servings
9.8 grams
1 serving
÷15
÷15
A package of cheddar cheese 9.8 grams of fat per serving