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Ratios Proportions Percents
Ratios Proportions Percents
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”
Ratios
ratiorate
rationrationalunit rate
RatiosRatios look like
fractions because they are fractions
= 1/61 : 2=
Types of Ratio ComparisonsPart 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 ComparisonsPart 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 of squares to circles is 3/6Ratio of squares to circles is 3 to 6Ratio 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
Ratio Examples
Part to
Part
Part to
Whole
ProportionsProportions are two equivalent
ratios,written as Part to Whole
1/2 2/4 3/6 4/8= = =
As one number or shape increases, the other number or shape increases by the same ratio
1/2 2/4 3/6 4/8
proportional
ProportionsTesting Proportions to see if they
are equivalent
26
39
1818Cross Multiply to see if they are equal
If they are the same, they are
equivalent AND
proportional!Use cross multiplication to test
proportions if you are given 2 fractions (or more)
ProportionsSolving a proportion when you only
have some information
Find the unknown number.Step 1:
26
x9=
L oo k
Proportions26
L k at the number directly above or below the unknown
number.
x9
Step 2:
=
Circle this number.
Proportions
L k at the number directly across from the circle
L oo kStep 3:
Draw a square around this number.
x9=2
6
Proportions26
Draw a triangle around the number above or below the
square.
x9
Step 4:
=
Proportions26
x9
Step 5: Fill in the template and solve
=
* = x = x9 6 2
x = 3*
Proportions26
x9
Solving using backtracking:
=
Step 1: Cross multiply
2 9 = 6 x* *18 = 6x
Proportions26
x9
Solving using backtracking:
=
Step 2: Tell the “story” of x
x6*
18
Proportions26
x9
Solving using backtracking:
=
Step 3: Backtrack!
x6*
186x = 3
Percents
Percent means parts per 100,and tells you a ratio "out of 100"
So 50% means 50 per 100
Ratios Proportions Percents
Ratios can be written as:1) 2 separated
with a ( : )
2) A
3) with the word
ratio of to is 3/6ratio of to is 3 to 6ratio of to is 3:6
Proportions are two equivalent ratios.
A is a way to compare or
more numbers.Proportions are written as p a r t to w h o le.
Ratio of squares to total figures is
When given 2 proportions:
When solving for an unknown:
Percent means parts per 100, and tells you a ratio "out of 100"
Ratios