Ratios and Proportions

- Chapter 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?

Proportion two equal ratios

- Check to see if its a proportion by comparing

the decimals - Check to see if they are equal by comparing the

fractions

Can we use the same numbers and create three

other proportions?

- Dont forget to check your proportions by

comparing the decimals or the fractions

Solving Proportions

- Cross multiplication
- Only works when there is an equal sign ()

between two fractions. - Verify that you are correct

Try these

- Use cross multiplication to solve
- Compare the fractions or decimals to check

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

Try this

- If 18 pieces of candy weigh 2.13 oz, how much

will 30 pieces of candy weigh? - Check by comparing decimals

Percents as Ratios

- Percent per 100
- Can we write 65 as a ratio?
- What is 3 as a ratio?
- What is as a percent?

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?

Write a proportion and solve.

- What is 8 of 14?
- 178 of what number is 49?
- 37 is 15 of what number?

Here are the proportions. YOU write the

questions.