1. DO NOW (not later): Compare the number of boys to girls in the class.
Free powerpoints at

2. The number of boys =
The number of girls =
If we compare boys to girls we get
boys to girls.

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

4. AIM:
What is a ratio?

5. 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?

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

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

8. 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.

9. Equivalent Ratios Simplify the following ratios: 4 to 8 10 to 8/
GCF = 4
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

10. The ratio 2 : 3 can be expressed as
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)

11. Practice problem # 1
(1) You have 100 different shirts. The ratio of blue to black shirts is a) Write the ratio of blue to black shirts 3 different ways. b) Write the ratio in simplest form. c) Explain what this ratio tells us. d) How many black shirts do you have?

12. Solution - # 
You have 100 different shirts. The ratio of blue to black shirts is 20 / 30
a) Write the ratio of blue to black shirts 3 different ways.
20 to 30 , 20 : 30, 20 30
b) Write the ratio in simplest form. 2 3

13. Practice Word Problems
You go to a party where the ratio of boys to girls is 28 to 56. Express the ratio of boys to girls in simplest form.
Explain what this ratio tells us.
28 / 56 = 1 / 2
The ratio of boys to girls is 1 to 2
(2) For every 1 boy there are 2 girls at the party.

14. 5-1
Objective: Solving proportions

15. A ratio is the comparison of two numbers written as a fraction.
An equation in which two ratios are equal is called a proportion.
A proportion can be written using colon notation like this
a:b::c:d
Or as the more recognizable (and useable) equivalence of two fractions.

16. Proportions To set up a proportion think part/whole part ______ part=
whole
whole
If you can travel 120 miles on 6 gallons of gas, how far can you drive on 8 gallons of gas?
(6)gas
(8)gas
______
______
6x=960
x=160 =
120miles
(x) miles

17. RATIOS & PROPORTIONS Are the following proportions?
FALSE – Not a proportion
FALSE – Not a proportion
TRUE – this is a proportion
TRUE – this is a proportion

18. RATIOS & PROPORTIONS
Find the missing numbers to make the following proportions.