Ratio

Bell WorkFind the slope

Slope = 0Slope =

Ratios

There are 3 ways to express ratios:

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

What is the ratio of cats to mice?Number of Cats:3Number of Mice:6Express the ratio as a fraction:Express the ratio in words:Express the ratio with a colon:3 to 63:6

TeamWinsLossesS.D. Padres1611L.A. Dodgers1813Chicago Cubs17142001 Spring TrainingList the wins to losses by the Cubs :17 to 14Wins to games played:17 to 31List the losses to wins by the Padres:11/16Losses to games played:11/27TeamWinsLossesS.D. Padres1611L.A. Dodgers1813Chicago Cubs17142001 Spring TrainingList the Dodgers wins to total games: 18 : 31List the Dodgers losses to wins:13 : 18Your 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

43/1343 to 13Comparing Ratios Seth and Nathan compared their CD collections. To determine who has a greater ratio of rock CDs to pop CDs, write the ratios.RockPopHip-hopSeth92316Nathan427025Seth:

= .375Nathan: = 0.6Write ratios as fractions.Write fractions as decimals to compare.Nathan has a greater ratio of rock to pop CDs.

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?Ratio is a way of comparing two or more quantitiesExamples:

Number of Red Smarties in a box compared to Blue

Number of girls in a class compared to boysFor exampleRED & BLUE Smarties6 BLUE3 REDThe Ratio of BLUE to RED Smarties is 6 to 3Blue : Red6 : 32 : 1The Ratio of BLUE to RED Smarties is 6. OrRED & BLUE Smarties6 BLUE3 REDThe Ratio of RED to BLUE Smarties is 3 to 6Red : Blue3 : 61 : 2The Ratio of RED to BLUE Smarties is 1:2For every RED Smartie, there are 2 BLUESSimplifying RatiosIn 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 factorTry to simplify these8:218:34:85:255:24:16:11:21:55:2 !!Sharing an amount in a given ratioBart and Maggie share a bag of 16 life savers in the ratio 3:1This means for every 3 life savers Bart gets, Maggie gets 1

412What 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 1200Express the ratio with a colon:300 : 1200

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:

2.There is 1 computer for every 4 students ORBring the fraction to lowest terms:

17Practice With Equivalent RatiosFind an equivalent ratio by dividing:

Divide by 30

# 1 # 2

Divide by 3 # 3

Divide by 25

Practice With Equivalent RatiosFind an equivalent ratio by multiplying:

Multiply by 5

# 4 # 5 # 6

Multiply by 12

Multiply by 6

Practice:Ratios worksheet