Ratios, Rates, and Unit Rates across the Universe An introduction

RATIOS A ratio makes a comparison. There are 3 green aliens and 4 purple aliens. The ratio of green aliens to purple aliens is 3 to 4.

RATIOS A ratio makes a comparison. The ratio of green aliens to total aliens is 3 to 7. The ratio of total aliens to purple aliens is 7 to 4.

RATIOS A ratio makes a comparison. Ratios can be written in three different ways. 3 to 4 3:4

RATES A rate is a ratio that compares quantities that are measured in different units. This spaceship travels at a certain speed. Speed is an example of a rate. Speed can be measured in many different ways. This spaceship can travel 100 miles in 5 seconds. 100 miles in 5 seconds is a rate.

RATES A rate is a ratio that compares quantities that are measured in different units. Rates are often written in fraction form. 100 miles in 5 seconds is a rate. It can be written as….. Miles Seconds

RATES A rate is a ratio that compares quantities that are measured in different units. One key word that often identifies a rate is PER. Miles per gallon, Points per free throw, Dollars per pizza, Sticks of gum per pack What other examples of rates can your group think of?

UNIT RATES Most of the time when we work with rates we use a unit rate. A unit rate compares a quantity to one unit of another quantity. This alien can walk at a rate of 10 miles in 2 hours. His speed is a unit rate of 5 miles per 1 hour or simply 5 miles per hour. Miles Hours Miles Hour =

UNIT RATES A unit rate compares a quantity to one unit of another quantity. These are all examples of unit rates. 2 eyes per alien 1 foot per leg 6 tentacles per head 1 tail per body 3 windows per spaceship 3 riders per spaceship 2 people riders per dog rider

Examples Rate: 150 space miles 2 minutes Unit Rate (Divide to get it): 150 ÷ 2 = 75 space miles per minute.

Find the Unit Rate Ashytn can read 88 pages in 4 hours. What is the unit rate? (How many pages can she read per hour?) 88 pages 4 hours 22 pages / hour

Using Unit Rates You can find the missing terms of equal ratios. Use the unit rate, and set it equal to another ratio. Solve for what is missing by dividing or multiplying.

Example Alissa’s car goes 25 miles per gallon of gasoline. How far can it go on 8 gallons of gasoline? 25 miles 1 gallon Unit Rate = 8 gallons x 8 25 x 8 = 200. Alissa’s car can go 200 miles on 8 gallons of gas.

Comparing Unit Prices Use division to find the unit prices of the two products in question. The unit rate that is smaller (costs less) is the better value.

Example Juice is sold in two different sizes. A 48-fluid ounce bottle costs $2.07. A 32-fluid ounce bottle costs $1.64. Which is the better buy? $ fl.oz $0.04 per fl.oz. $ fl.oz $0.05 per fl.oz. The 48 fl.oz. bottle is the better value.

Comparing Unit Prices Use division to find the unit prices of the two products in question. The unit rate that is smaller (costs less) is the better value.

HOMEWORK TIME