2. estimate and find solutions to application problems involving proportional relationships such as similarity, scaling, unit costs, and related measurement units.[7.3.B]

3. § What are these? § Are they equal? § Prove it to me? § Can you show me how you prove it § How do you read it?

4. A proportion is nothing more than and equivalent ratios which are nothing more than equivalent fractions

5. To find a proportion you may use the loop method How do you get from 4 to 12? Multiply by 3; 4 x 3 = 12

6. The relationships on the top and the bottom must be the same; therefore, if you multiply by 3 on the bottom you must multiply by three on the top.

7. A proportion is an equation that shows that two ratios are equal. o You can solve the proportion using algebra or you can solve it just as you solve equivalent fractions. o To set up a proportion problems you must first set up the labels. o You then must put the same label on the top on each side o Then replace the labels with numbers and solve.

8. If there are 30 students in a class and the are are 16 girls what is the ratio of girls to boys

9. Now suppose there are 42 boys in a class. How many girls are in the class. You can use a proportion to set up and solve this problem.

10. You know that the ratio of girls to boys is 16 to 14. therefore we can use that ratio to find the number of girls in a 42 boy class.

11. How do you get from 14 to 42? Multiply by 3.

13. You must multiply 16 times 3

14. Therefore if there are 42 boys there will be 48 girls