1. Lesson EQ
How do you use proportions to convert measurements, find the unknown side length of polygon or real life objects, and interpret and construct scale models?

2. Converting Units
We can also use cross products to solve proportions to convert units.
In order to do this we must know the units, though.
Please copy the following two slides neatly into your work.
You will be quizzed separately on each set of information.

3. Customary System Measurements
Length:
12 inches = 1 foot
3 feet = 1 yard
5280 yards = 1 mile
Weight:
16 oz = 1 lb
2000 lb = 1 ton
Capacity
8 fl oz = 1 cup
2 cups = 1 pint
2 pints = 1 quart
4 quarts = 1 gallon

4. Metric System 1 millimeter = 0.001 meter 1 centimeter = 0.01 meter
1 decimeter = 0.1 meter
1 meter
1 dekameter = 10 meters
1 hectometer = 100 meters
1 kilometer = 1,000 meters

5. Analyze Units
To analyze units we will be given a value in one unit and be told to change it into a different unit.
We will set these units as a ratio.
We will set that ratio equal to a ratio from our measurement notes.
We will solve for the missing value.
Make sure that the units match in each ratio.

6. Analyze Units
The average American eats 23 pounds of pizza per year. Find the number of ounces of pizza the average American eats per year.
23 lb x oz
We know 16 oz = 1 lb. Set up a proportion
23 lb = 1 lb x oz oz
Cross multiply: 23 • 16 = 1x
Simplify: 368 oz

7. Analyze Units
Aihua drinks 4 cups of water a day. Find the total number of fluid ounces of water she drinks per day.
4 cups x fl oz
8 fl oz = 1 cup ~ Set up a proportion
4 cups = 1 cup x fl oz fl oz
Cross multiply: 4 • 8 = 1x
Simplify: 32 fl oz

8. Analyze Units
A model airplane flies 22 feet in 2 seconds. How many inches did the airplane fly?
22 ft x in
12 inches = 1 foot ~ set up proportion
22 ft = 1 ft x in in
Cross multiply: 22 • 12 = 1x
Simplify: 264 inches

9. Your Turn
A fish swims 13 centimeters. How many meters did the finish swim?
13 cm x m
1 cm = 0.01 m ~ set up a proportion
13 cm = 1 cm x m m
Cross multiply: 13 • 0.01 = 1x
Simplify = 0.13 m

10. Try Another 8 gallons equals how many quarts? 8 gal x qt
4 quarts = 1 gallon
8 gal = 1 gal x qt qt
Cross multiply: 8 • 4 = 1x
Simplify 32 quarts

11. Additional Examples

12. Homework