Disclaimer: In this presentation, there are slides that are interactive (meaning, you will be able to type in statements or answers). Anything that you type in that is inappropriate will result in a discipline referral.
Understanding Proportions
A proportion is two ratios that are equal to each other. The two ratios can be written as fractions, decimals, or percents. Proportions can help us compare two parts of a whole. For example, if 4 out of 10 students are girls, the proportion of girls is 4/10. In proportion problems, we use cross multiplication to solve for an unknown value. For example, if a = 4/5, what is 5a? The answer is 5a = 4*5 = 20.
proportions
Ratio: A comparison of two numbers or measurements, written as a fraction.
Proportion: An equation that states that two ratios are equal.
Scale: A ratio that compares a length, area, or other measurement on a map to the actual distance or area on the ground.
What is the definition of proportion?
- The total amount of something
- The average value of a set of numbers
- A comparison between two or more quantities
Which symbol is used to represent proportionality?
If 20 apples cost $10, how much would 30 apples cost?
If it takes a car 2 hours to travel 120 miles, how long would it take for the same car to travel 180 miles at the same speed?
If a recipe requires 2 cups of flour and serves 4 people, how many cups of flour would be needed to serve 8 people?
A granola recipe requires you to use 5 cups of oats for every 3 cups of almonds. How many cups of oats would be needed if you used 12 cups of almonds?
When trying to find the perfect shade of blue for his room, Joe mixed 20 parts of blue with 8 parts of black. Joe will need just a little bit more paint. How much blue will he need if he only uses 2 parts of black?
A hybrid car can go 141 miles on 3 gallons of gasoline. How many miles can it travel with 9 gallons of gasoline?
A hybrid car can go 141 miles on 3 gallons of gasoline. How many miles can it travel with 9 gallons of gasoline?
Jose collects stamps. He has 7 used for every 4 new stamps. If he has 28 new stamps, how many used stamps does he have?
Marcie can mow 9 lawns every 14 hours. How many lawns can she mow in 49 hours?