3 9 Proportions Goal to solve word problems

3. 9 Proportions • Goal to solve word problems involving proportions

Vocabulary ratio: a comparison of two numbers through division often expressed as a fraction. Proportion: An equation that states that two ratios are equal

To Solve Proportions… • Cross multiply and set their products = to each other • Ex: a = b • c d • so ad = cb

Ex 1: y = 20

Ex 2:

Ex 3:

When to set up a proportion • Comparing units • Converting units • Has the word “per”, “ratio”, “rate”, or “out of”

Steps to Solving Word Problems involving Proportions 1. Read the word problem twice 2. Identify the comparison of units and write the units in fraction form 3. Set up your proportion keeping units in proper place (convert units if need be) 4. Cross multiply 5. Set products equal to each other 6. Solve for the variable

Ex 4: On a road map 3 inches represents 40 miles. If two cities are 10 inches apart on the map, how many miles is it from one to the other?

Ex 5: The ratio of boys to girls on the swim team is 5 to 4. How many girls are on the team if there are 65 boys?

Ex 6: Ryan can type 4 pages in 15 minutes. At this rate, how many pages can he type in 2 hours?

Ex 7: A survey found that 60 out of every 85 people in a city take public transportation to work. Out of 595 people, how many take public transportation to work?

Assignment Page 150 (10 -24 even and 25 -38 all )