DO NOW not later:

1
DO NOW (not later)

• Compare the number of boys to girls in the class.

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
Its 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.

• 68 , 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
• 8 to 10

• 4 / 4 1 1 to 2
• 8 8 / 4 2

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
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
Compound Ratios

• A ratio that compares more than 2 quantities is
  called a compound ratio.
• Example
• A cake recipe says the ratio of cups of milk,
  sugar, and batter are 124.
• This means that there is one cup of milk for
  every two cups of sugar and four cups of batter.

12
A bag contains 18 yellow, blue, and red marbles.
The ratio of yellow to blue to red marbles is 4
2 3.

• Write the ratio of yellow to blue marbles in
  simplest form.
• What is the ratio of yellow to red marbles?
• How many yellow marbles are there?

Yellow Blue Red is 4 2 3 Since any
multiple of this is an equivalent ratio, this can
also be written as 4x 2x 3x Let 4x yellow,
2x blue , 3x red 4x 2x 3x 18 9x
18 X 2 Since the question asks for yellow
marbles, there are 4x or 4 (2) 8 yellow
marbles.
4 2 can be simplified to 2 1
4 3
13
Practice problem 1

• (1) 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.
• b) Write the ratio in simplest form.
• c) Explain what this ratio tells us.
• d) How many black shirts do you have?

14
Solution - 1 ?

• 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
• c) Explain what this ratio tells us. For every
  two blue shirts, there are 3 black shirts.
• d) How many black shirts do you have?
• 2x 3x 100
• 5x 100
• x 20
• There are 2x black shirts so 2
  (20) 40 black shirts

15
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.

16
Practice Word Problems

• Mindy has 72 candy bars. If the ratio of Mars to
  Snickers is 84, Find the number of each type of
  candy.
• Explain what this ratio tell us.

17
Challenge Question

• The perimeter of a rectangle is 500 feet. The
  ratio of the base and height is 32. What is the
  measure of the height?

18
(No Transcript)
19
(No Transcript)
20
(No Transcript)
21
(No Transcript)
22
(No Transcript)
23
(No Transcript)
24
PRACTICE

• What is the ratio of 6 days to 3 weeks?
• What is the ratio of 80 minutes to 2 hours?
• Are 35 and 1220 are equal ratios.
• The angles of a triangle are in the ratio of
  235. What size is each of the angles?

25
PRACTICE
26
PRACTICE
27
PRACTICE

• The Canadian dollar was 73.69 cents American.
  About how many American dollars can you purchase
  for 150 Canadian?