# Ratios And Proportions

### By: Eric Long

## The 2 Types Of Ratios

*Part to Part which is a part of the total number with another part of the total number

Ex: There are 25 students in the class, 12 are boys and 13 are girls

Or

*Part to Whole which is a part of the total number with the total number

Ex: In a classroom, 13 students are girls and there are 25 students in the classroom

## Proportionality: To check if it's proportional or non-proportional

## Proportional: Equal Ratios | ## Non-Proportional: Ratios are not equal | ## Solving Proportions: Scale Factor 2*3 6 ----- = ---- 4*3 12 Or Cross Multiply Look At The Picture Above *These are not the only ways to solve, these are only the major ways to solve |

## How To Set Up Proportions

Number Word/Unit Number Word/Unit

---------------------------- = ----------------------------

Number Word/Unit Number Word/Unit

Ex: 3 Books 6 Books

------------- = -------------

6 Dollars 12 Dollars

*This is not the only kind of set up! This is only the regular set up and there are many more like the percent proportion, etc

## The Types Of Proportions

2.Same 2 Words Twice: 3 Numbers Are Given(Some May Be Inferred); Regular Set Up

3.Constant Of Proportionality And Unit Rate: Amount For One Unit; Regular Set Up But With A Ratio Having A Unit Of One

4.Measurement And Scale Drawing: Changing Between 2 Different Units Or A Picture Of A Smaller Model/Drawing; Regular Set Up But With Different Measurement Units

5.Similar Figures: Same Shape, Different Size; Regular Set Up But Words May Be Long/Short, Length/Width, Etc

6.Percent: If There Is A Percent Or Percent Sign Use The Percent Proportion Which Is Part Over Whole, Percent Over 100