RATIO
(1) is how much of one thing there is compared to another thing
There
are 3 blue triangles to 2 red triangles
(2) comparison
between two different things
à To compare the quantity of 2 or
more things
There
are 3 ovals to 1 star
(3) comparison
of two or more quantities
There are 2 squares to 1 triangle
and 2 squares to 3 circles
There are 1 triangle to 3 circles
Symbol for ratio
It is represented by TWO or more numbers
with a colon:
Number1: Number2
How to use ratio to compare?
1 : 2
There is 1 square for every 2
circles.
The ratio of square to circle is 1
to 2
1
: 2
There are 2 circles for every
square.
The ratio of circles to square is
2 to 1.
The position of the numbers of the ratio must relate to the items being compared.
The ratio’s position of the numbers is important -> 1:2 is not 2:1
Ratio is comparison of
numbers, there is no unit of measure.
Comparing more than 2 Ratios
There are 1 square, 2 circles and 4 triangles in
the box.
1 :
2 : 4
The ratio of number of square to number of circles to number of
triangles is 1:2:4.
Equivalent Ratios
Example:
Example
What is the missing number in these equivalent
ratios?
2 : 5 =
12 : ____
Method
Step1: Divide the bigger number with
the smaller number
12
÷ 2 = 6
Step2: Multiply the equivalent ratio’s number with answer from step1.
Step3: Answer the question
The missing number is 30.
Ratio in its simplest form
What is the ratio 5: 15 in its simplest form?
5 is the common factor of 5 and 15.
Method1
Step1: Divide the number in the ratio
5/15 = 1/3
Answer: 1 : 3
The ratio 5 : 15 in its simplest form is 1: 3.
Example
What is the ratio of 55 min to 30 min in its
simplest form?
Ratio → 55 : 30
55/30 = 11/6
→11 : 6
Method2:
Lowest Common Multiple(LCM) Method
Example:
What is the ratio of 1hour 15mins to 45 min in
its simplest form?
Change 1 hour 20 min to mins for comparison
1 hour = 60 min, 1 hour 20 min = 80 mins
Method
Step1: Draw the LCM grid and fil
in the value.
The ratio 75 : 45 in its simplest form is 5 : 3
Practice
What is the ratio 10 : 6 : 16 in its simplest
form?
Answer : 5:3:8
Ratio and Fractions
A fraction is a part
of a whole.
Whole - 1 Part
- ½
In ratio, the larger number is the whole and the
small number is the ‘Part’
RATIO FRACTION
A ratio is a
comparison a fraction is the part of a whole
Ratio, Fractions, As a whole(Total)
There are 1 square and 2 circles in the box
Total numbers of shapes in the box is 3 (1
square and 2 circles)
Ratio
of number of square to circle is 1 : 2
Ratio
of number of circle to square is 2: 1
Ratio
of number of square to the total numbers of shapes 1 : 3
Ratio
of number of circle to the total number of shapes 2 : 3
There
are twice as many circles as square
There
are ½ as many squares as circles
1/3
of the shapes in the box are square
2/3
of the shapes in the box are circle
The ratio of the number of square to circles to
shapes in box is 1:2:3
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