The document defines and provides examples of ratios. Key points: - A ratio compares two quantities and expresses their relationship. Order matters in a ratio (e.g. 2 to 3 is not the same as 3 to 2). - Ratios can be written in three equivalent forms: a:b, a to b, or as a fraction a/b. - Equivalent ratios can be formed by simplifying ratios (reducing to lowest terms) or multiplying the original ratio by a number. - Examples show calculating and writing ratios for various scenarios involving groups of objects.

1. RATIOS

2. DO NOW (not later):
 Compare the number of boys to girls
in the class.

3.  The number of boys =
 The number of girls =
 If we compare boys to girls we get
___ boys to _____ girls.

4. What do we call a comparison between
two or more quantities?
RATIO
We just found the
RATIO of boys to
girls.
Is the ratio of
girls to boys
the same ?
No, when writing a ratio, ORDER matters.

5. Essential Question:
What is a ratio?

6. It’s Friday night and your friends are
having a party……
The ratio of girls to guys is 2 to 12.
Would you want to attend the
party?

7. How many basketballs to footballs are
there?
 For every 4 basketballs
there are 6 footballs.
 The ratio is 4 to 6.

8. What are some other ways we
can write the ratio of basketball
to footballs?
 4 to 6
 4 : 6
 4
6
First quantity to Second quantity
First quantity : Second quantity
First quantity divided by the second
quantity (as a fraction).
Every ratio can be written in 3 ways:
Careful!!
Order matters in a ratio.
4 to 6
Is NOT the same as
6 to 4

9. Write the ratio of sandwiches to coke bottles
3 different ways. 6:8 , 6 to 8, and 6
8
Since a fraction can be simplified, We can simplify the ratio 6/8
to 3/4. The ratio of sandwiches to coke bottles can also be
expressed as 3 : 4 or 3 to 4.
In other words, ratios can be simplified to form
equivalent ratios.

10. Equivalent Ratios
 Simplify the following ratios:
 4 to 8
 10 to 8
 8 to 10
Step 1 – Write the ratio as a fraction
Step 2 – Simplify the fraction (Find the greatest common factor (GCF) of
both numbers and divide the numerator and denominator by the GCF).
Step 3 – Write the equivalent ratio in the same form as the question
4 = 4 / 4 = 1 = 1 to 2
8 8 / 4 2
GCF = 4

11. Equivalent Ratios can be formed by
multiplying the ratio by any number.
 For example, the ratio 2 : 3 can also be
written as
 4 : 6 (multiply original ratio by by 2)
 6 : 9 (multiply original ratio by by 3)
 8 : 12 (multiply original ratio by by 4)
The ratio 2 : 3 can be expressed as
2x to 3x (multiply the original ratio
by any number x)

12. Now you try…
1. There are 6 goldfish and 5 mollys in the fish tank.
What is the ratio of goldfish to all fish in the tank?
2. Brad has 2 brothers and 4 sisters. What is the
ratio of boys to girls in his family?
3. Julie has 8 cats, 5 dogs, 4 pigs, and 7 horses on her
farm.
a) What is the ratio of cats to dogs?
b)What is the ratio of dogs to horses?
c) What is the ratio of pigs to cats?
d)What is the ratio of cats to all animals on the
farm?