PROPORTIONS

Section 1.6We will use proportions to analyze proportional

relationships and to solve

real-life problems.

WHAT THE HECK IS A PROPORTION?

WHAT IS A PROPORTION USED FOR?

To find an ______ value in one ratio when given another ______ ratio.

HOW DO WE SOLVE A PROPORTION?

We find the ________, where we multiply the numerator of one ratio with the

denominator of the other ratio.

*Step 1: Find the cross products

*Step 2: Compare the cross products

2 = 103 15

LET’S PRACTICE DETERMINING IF TWO RATIOS ARE PROPORTIONAL

30 30

YES!

*Step 1: Find the cross products

*Step 2: Compare the cross products

15 = 912 6

LET’S PRACTICE DETERMINING IF TWO RATIOS ARE PROPORTIONAL

NO!

Is the following ratio proportional?

4 = 165 20

WHITE BOARD TIME!!

Is the following ratio proportional?

6 = 1810 30

WHITE BOARD TIME!!

Is the following ratio proportional?

1 = 48 24

WHITE BOARD TIME!!

24 32

Try on your Own

1. The ratio of 7th grade students to 8th grade students in a soccer league is 17:23. If there are 200 students in all, how many are in the 7th grade?

Try on your Own

2. After 2 hours, the air temperature had risen 8 degrees. Write and solve a proportion to find the amount of time it will take at this rate for the temperature to rise and additional 13 degrees.

Use Unit RateYou can also use the unit rate to write an equation

expressing the relationship between two proportional quantities.

Example: Olivia bought 6 containers of yogurt for $7.68. Write an equation relating the cost c to the number of yogurts y. How much would Olivia pay for 10 yogurts at this same rate?

Practice

Solve each proportion:

1. k = 32 7 56

2. 3.2 = n 9 36

3.Evarado paid $1.12 for a dozen eggs at his local grocery store. Determine the cost of 3 eggs.

Essential Question

How do you solve a proportion?

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