MATH 5Fourth Grading Period

RATIO

RATIOThe comparison between two

quantities

The number in a RATIO are the TERMS of Ratio

How will you read Ratios?Example:

Six to eight or six is to eight

How will you write Ratios?Example:

Ratios can be written in 3 ways

Using the ":" (colon)to separate the values:

  6:8

     

Instead of the ":" you can use the word "to“ or “is to”:

  6 to 8 or 6 is to 8

     

Or write it like a fraction:

  68

Using RatiosThe trick with ratios is to always multiply or divide the numbers by the same value.

Example:4 : 5 is the same as 4×2 : 5×2 = 8 : 10

4:5 = 8:10

"Part-to-Part" and "Part-to-Whole" Ratios

The examples so far have been "part-to-part" (comparing one part to another part).

But a ratio can also show a part compared to the whole lot.

Example: There are 5 pups, 2 are boys, and 3 are girls.

Part-to-Part:The ratio of boys to girls is 2:3 or 2/3   The ratio of girls to boys is 3:2 or 3/2   Part-to-Whole:The ratio of boys to all pups is 2:5 or 2/5   The ratio of girls to all pups is 3:5 or 3/5 

Let’s try

What is the ratio of circles to triangles

What is the ratio of triangles to circles

What is the ratio of triangles to all shapes

What is the ratio of circles to all shapes

4 3:

3 4:

3 7:

4 7:

How to simplify Ratios?The terms of ratio a:b in simplest

Form must be whole numbers Greater than zero. Remember To reduce the terms similar to

Reducing fractions.

Simplify the following ratios:

a. 18:27b. 1 ¼ : 1 ½

a. 18:27

a. The GCF of 18 and 27 is 9. So divide both 18 and 27 by 9.

18:27 18 ÷ 9= 227 ÷ 9= 3 2:3

Therefore the simplest form of 18:27 is 2:3

b. Change 1 ¼ and 3 ½ into improper fractions.

1 ¼ : 3 ½ = 5/4 : 7/2Find their LCM (less common denominator)

5/4 : 7/2 = 5/8 : 14/8

= 5:4 is the simplest form

Or just simply divide the fractions

5/4 : 7/2

54

72

÷ x= 54

27

2/7 is the reciprocal of

7/2

=1028

514

or

5:14Simplest form

c. Multiply both terms by 10 to make them whole

numbers.3.6 : 9 = 36 : 90

3.6 x 10 = 36 9 x 10 = 90

36 : 90

2:536 ÷ 18 = 290 ÷18 = 518 is their 

GCFSIMPLEST FORM

ANOTHER EXAMPLE

4.5 : 54.5 X 10 = 45

5 X 10 = 50

45 : 50WHAT IS THE GCF OF 45 and 50?

545÷5 = 950÷5=10 = 9:10

Lets review:

It is the comparison between two quantities?

It is the numbers in Ratio?

Don’t Get Mad!!

Take it easy

It’s simple!

THE END