Ratios

Proportions

Percents
Ratios

Proportions

Percents
Ratios
A ratio is a way to compare two or more
numbers
Ratios can be written as:
1). 2 numbers separated by a colon :

2). A fraction

3). With the word “to”

ratio
rate
ration
rational
unit rate
Ratios
Ratios look like fractions
because they are fractions

1 : 2=

= 1/6
Types of Ratio Comparisons

Part to Part

The ratio of strawberries to
oranges is 2 to 3.

The ratio of oranges to
strawberries is 3 to 2.
Types of Ratio Comparisons

Part to Whole

The ratio of kittens to total pets
is 3 to 8.

The ratio of puppies to all pets
is 5 to 8.
Ratio Examples

Ratio of squares to circles is 3/6

Ratio of squares to circles is 3 to 6

Part to
Part

Ratio of squares to circles is 3:6

Ratio of squares to total figures is 3:10
Ratio of circles to total figures is 6/10

Part to
Whole
Proportions
Proportions are two equivalent ratios,
written as Part to Whole

1/2

=

2/4

=

3/6

=

4/8
proportional
As one number or shape increases, the
other number or shape increases by
the same ratio

1/2

2/4

3/6

4/8
Proportions
Testing Proportions to see if they are
equivalent
Cross Multiply
to see if they
are equal

18
2
6

18
3
9

If they are the
same, they are
equivalent AND
proportional!

Use cross multiplication to test
proportions if you are given 2 fractions (or
more)
Proportions
Solving a proportion when you only have
some information

2
6

=

x
9

Step 1:
Find the unknown number.
Proportions
2
6

=

x
9

L oo k

Step 2:
L

k at the number directly above or
below the unknown number.
Circle this number.
Proportions
2
6
Step 3:
L

=

x
9

L oo k

k at the number directly across from
the circle
Draw a square around this number.
Proportions
2
6

=

x
9

Step 4:
Draw a triangle around the number
above or below the square.
Proportions
2
6

x
9

=

Step 5:
Fill in the template and solve


9

*

 6 * 2
x=3

=x

=x
Proportions
2 = x
6

9

Solving using backtracking:
Step 1: Cross multiply

2 * 9 = 6 *x
18 =
6x
Proportions
2 = x
6

9

Solving using backtracking:
Step 2: Tell the “story” of x

6
*

x

18
Proportions
2 = x
6

9

Solving using backtracking:
Step 3: Backtrack!

6
*
x
x=3

18

6
Percents
Percent means parts per 100,
and tells you a ratio "out of 100"

So 50% means 50 per 100
Ratios

Proportions

A
is a way to
compare
or more
numbers.
Ratios can be written as:
1) 2
separated
with a
(:)

Proportions are two
equivalent ratios.
Proportions are written as p
a r t to w h o le.

2) A
3) with the word
When given 2 proportions:
ratio of

to

is 3/6

ratio of

to

is 3 to 6

ratio of

to

is 3:6

Ratio of squares to
total figures is

When solving for an unknown:

Percents
Percent means parts
per
100, and tells you a ratio "out of
100"

Ratios, prop % with cloze