Bell Work

Find the slope

Slope = 0Slope =

3

2

Ratios

There are 3 ways to express ratios:

As a fraction - ¾Using a colon - 3:4Using the word “to” - 3 to 4

What is the ratio of cats to mice?

Number of Cats: 3

Number of Mice: 6

Express the ratio as a fraction:

Express the ratio in words:

Express the ratio with a colon:

3 to 6

3:6

63

Team Wins Losses

S.D. Padres 16 11

L.A. Dodgers 18 13

Chicago Cubs 17 14

2001 Spring Training

List the wins to losses by the Cubs : 17 to 14

Wins to games played: 17 to 31

List the losses to wins by the Padres: 11/16

Losses to games played: 11/27

Team Wins Losses

S.D. Padres 16 11

L.A. Dodgers 18 13

Chicago Cubs 17 14

2001 Spring Training

List the Dodgers wins to total games: 18 : 31

List the Dodgers losses to wins: 13 : 18

Your face uses about 13 muscles to smile and about 43 muscles to frown. Write the ratio of muscles used for frowning to muscles used for smiling in three different ways.

43:13

43/13

43 to 13

Comparing Ratios Seth and Nathan compared their CD

collections. To determine who has a greater ratio of rock CDs to pop CDs, write the ratios.

Rock Pop Hip-hop

Seth 9 23 16

Nathan 42 70 25

Seth:

= .375

Nathan: = 0.6

Write ratios as fractions.

Write fractions as decimals to compare.

Nathan has a greater ratio of rock to pop CDs.

Pop

Rock

23

9

Pop

Rock

70

42

How do you change a fraction into a decimal?

Divide the denominator into the numerator

OR on your calculator hit 9 divided by 24 = .375

24

9

Ratio?

Ratio is a way of comparing two or more quantities

Examples:

◦Number of Red Smarties in a box compared to Blue

◦Number of girls in a class compared to boys

For example

RED & BLUE Smarties

6 BLUE 3 RED

“The Ratio of BLUE to RED Smarties is 6 to 3

Blue : Red

6 : 3

2 : 1

“The Ratio of BLUE to RED Smarties is 6

…. Or…

RED & BLUE Smarties

6 BLUE 3 RED

“The Ratio of RED to BLUE Smarties is 3 to 6”

Red : Blue

3 : 6

1 : 2

“The Ratio of RED to BLUE Smarties is 1:2”

“For every RED Smartie, there are 2 BLUES”

Simplifying Ratios

In the Smarties example, we changed 6:3 to 2:1

This is called Simplifying a ratio

We did it by dividing each number by 3

3 was the largest common factor

Try to simplify these

8:218:34:85:255:2

4:16:11:21:55:2 !!

Sharing an amount in a given ratio

“Bart and Maggie share a bag of 16 life savers in the ratio 3:1”

This means “for every 3 life savers Bart gets, Maggie gets 1”

4 12

What is a ratio?

Example: There are 300 computers and 1200 students in our school. What is the ratio of computers to students?

Express the ratio in words:

Express the ratio as a fraction:

A ratio is a comparison

of two quantities.

300 to 1200

Express the ratio with a colon: 300 : 1200

1200300

How many students are there for one computer?

Equivalent ratios make

the same comparison.

What is an Equivalent Ratio?

1.There are 300 computers for 1200 students

Express the ratio as a fraction:

1200300

2.There is 1 computer for every 4 students

OR

Bring the fraction to lowest terms:

1200300

41

=

Practice With Equivalent Ratios

Find an equivalent ratio by dividing:

9030

Divide by 3031

= # 1

# 2 1215

45

= Divide by 3

# 3300125

125

= Divide by 25

30903030

÷÷

=

312315

÷÷

=

2530025125

÷÷

=

Practice With Equivalent Ratios

Find an equivalent ratio by multiplying:

410

Multiply by 554510

x x

= # 4

# 5

# 6

2050

=

37

12 x 312 x 7

=3684

= Multiply by 12

2011

6 x 206 x 11

=12066

= Multiply by 6

Practice:Ratios worksheet