1. Formulas, Proportion, and Variation
Chapter 4 Section 2
Formulas, Proportion, and Variation

2. What is the relationship between proportions and unit conversions?
Essential Question
What is the relationship between proportions and unit conversions?

3. What is a ratio?
Ratio: Comparison of two quantities that have the same units
Example:
20 dollars to 35 dollars
A mixture of 20 mL of water and 8 mL of alcohol.
What is the ratio of water to alcohol
What is the ratio of alcohol to water?

4. What is a rate? Rate: special type of ratio
Example: John drove his car for 336 miles with a full 13-gallon tank of gas. What is the rate in miles per gallon?
Example: What is the unit rate in calories per gram of fat in 1 medium bag of fries at Burger King? At McDonalds?

5. Unit Price Comparison
The Computer Warehouse is having a sales on black print cartridges. A 6-pk is selling for $96, while the 8-pk is selling for $136.
What is the unit price of each choice?
Which is a better buy? How does unit price come into play when you compare prices?

6. What is a proportion?
Proportion: an equation of two ratios or rates
Example: If 2-lbs of flour costs $3, then how much does it cost for 6-lbs of flour?
Example: Out of the 3000 people surveyed, people watched the Bachelor last Wednesday. With this rate, how many out of the 15,000 people watched the show?

7. Proportion – more examples
Example 3: Your car can drive 52 miles on 2 gallons of gas. Assuming the same rate, how many miles can it drive on 8 gallons of gas?
Example 4:
(4500 mg/560 cm^3) = (x mg/1 cm^3)