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## Ratios

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**Ratio is a way of comparing two or more quantities**• Examples: • Number of oranges to apples • Number of girls in a class compared to boys Ratio?**There are 3 ways to express ratios:**As a fraction - ¾ Using a colon - 3:4 Using the word “to” - 3 to 4**What is the ratio of cats to mice?**3 Number of Cats: 6 Number of Mice: Express the ratio as a fraction: 3 to 6 Express the ratio in words: Express the ratio with a colon: 3:6**2001 Spring Training**List the wins to losses by the Cubs : 17 to 14 17 to 31 Wins to games played by the Cubs: List the losses to wins by the Padres: 11/16 Losses to games played by the Padres : 11/27**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. Nathan has a greater ratio of rock to pop CDs. Seth: = .375 Write ratios as fractions. Nathan: = 0.6 Write fractions as decimals to compare.**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**Ratio Example Problems**RED & BLUESmarties Blue : Red 6 : 3 Which symplifies to 2 : 1 6 BLUE 3 RED “The Ratio of BLUE to RED Smarties is 6 to 3 “The Ratio of BLUE to REDSmarties is 6**RED & BLUESmarties**Red : Blue 3 : 6 “For every RED Smartie, there are 2 BLUES” 1 : 2 6 BLUE 3 RED …. Or… We can compare Red to Blue Smarties! “The Ratio of RED to BLUESmarties is 1:2” “The Ratio of RED to BLUE Smarties is 3 to 6”**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 Simplifying Ratios**8:2**18:3 4:8 5:25 5:2 4:1 6:1 1:2 1:5 5:2 !! Try to simplify these**“Bart and Maggie share a bag of 16 life savers with the**ratio of 3:1” This means “for every 3 life savers Bart gets, Maggie gets 1” Sharing an amount in a given ratio 4 Lifesavers for Maggie 12 Lifesavers for Bart**What is a ratio?**Example: There are 300 computers and 1200 students in our school. What is the ratio of computers to students? A ratio is a comparison of two quantities. Express the ratio in words: 300 computers to 1200 students Express the ratio with a colon: 300 computers : 1200 students Express the ratio as a fraction: How many students are there for one computer?**What is an Equivalent Ratio?**1.There are 300 computers for 1200 students OR 2.There is 1 computer for every 4 students Express the ratio as a fraction: Equivalent ratiosmake the same comparison. Bring the fraction to lowest terms:**Practice With Equivalent Ratios**Find an equivalent ratio by dividing: # 1 Divide by 30 # 2 Divide by 3 # 3 Divide by 25**Practice With Equivalent Ratios**Find an equivalent ratio by multiplying: # 4 Multiply by 5 # 5 Multiply by 12 # 6 Multiply by 6