1. 4.1 Ratio and Proportion Ratio – comparison of two numbers by division. –Can be written: a to b a : b where b ≠ 0. If a and b represent quantities measured in different units, then the ratio of a to b is a rate. A unit rate is a rate with a denominator of 1. –Ex.

2. Using Unit Rates Find the rate (cost per ounce).

3. Converting Rates A cheetah ran 300 feet in 2.92 seconds. What was the cheetah’s speed in miles per hour? You need to convert feet to miles and seconds to hours.

4. Solving Proportions A proportion is an equation that states that two ratios are equal. a = c for b ≠ 0 and d ≠ 0. b d You read this proportion as “a is to b as c is to d”. The extremes of the proportion – are a and d. The means of the proportion – are b and c. Another way you can see this proportion written is a : b = c : d.

5. Cross Products The products ad and bc are the cross products of the proportion For example,

6. Using Cross Products Use cross products to solve the proportion

7. Using Multi-Step Proportions Solve the proportion

8. More Practice!!!! Textbook – p. 185 #2 – 28 even, p. 186 #32 – 36 even. Homework – Worksheet 4.1