1. Ratios and Proportions
Chapter 2

2. Ratio: comparison of two numbers
I got 21 out of 24 questions correct!
Write this ratio as a fraction, with a colon, or as a decimal.
Fraction
With a colon
As a decimal
How do we find the decimal?

3. Proportion: two equal ratios
Check to see if it’s a proportion by comparing the decimals
Check to see if they are equal by comparing the fractions

4. Can we use the same numbers and create three other proportions?
Don’t forget to check your proportions by comparing the decimals or the fractions

5. Solving Proportions Cross multiplication
Only works when there is an equal sign (=) between two fractions.
Verify that you are correct

6. Try these Use cross multiplication to solve
Compare the fractions or decimals to check

7. Set up a proportion to solve
If Julie pays $4.00 for ½ pound of ham at the deli, how much will 1.25 lbs cost?
Units must be aligned

8. Try this
If 18 pieces of candy weigh 2.13 oz, how much will 30 pieces of candy weigh?
Check by comparing decimals

9. Percents as Ratios Percent: per 100 Can we write 65% as a ratio?
What is 3% as a ratio?
What is as a percent?

10. Solve percent questions!
The proportion can be used to
answer the question 18 is what percent of 45?
Remember:
Jean made a 28 out of 35 on a test. What percent did she get correct?
36 is what percent of 50?

11. Write a proportion and solve.
What is 8% of 14?
178% of what number is 49?
37 is 15% of what number?

12. Here are the proportions. YOU write the questions.