Solving a Proportion Problem

A Ratio and a Proportion

Ratio: The relationship in quantity, amount, or size between two or more things. Typically expressed as a quotient of two mathematical expressions (i.e. A FRACTION). For example:

Proportion: An equation that equates two ratios (i.e. TWO EQUAL FRACTIONS). For example:

ab

a cb d

Proportional

Note: If y = 0, then x = 0. Thus, all proportional relations must contain the point (0,0).

Example

Is the relation below proportional?

x 2 4 8 9

y 3 10 12 15

Using a Table to solve a Proportion Question

Toby uses seven tubes of toothpaste every ten months. How many tubes would he use in 5 years?

5 years = 5x12 = 60 months

Months Tubes

10 7

60 ? x6 x6

42

42 Tubes

Using an Equation to solve a Proportion Question

Toby uses seven tubes of toothpaste every ten months. How long would it take him to use 100 tubes?

142.86 Months

7 100

10 x

Tubes

Months

10 100 7

You learned this method

in middle school. Can

you prove/justify

that it works?

Using a Diagram to solve a Proportion Question

One more way to organize your work for 2-99

0x

20

6

15

10.8

36

14.1

y

x 1.8

x 1.8÷ 1.8

= 27

7.83 =