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Of the 1800 students who come to school, one-fifth walk, 35% come by bike, the rest by car. How many students come to school by car? If twice as many students walk home as those going in a car, how many would this be? (assuming all who biked, bike home). 810. 780. Ratios. Lesson Objective.
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Of the 1800 students who come to school, one-fifth walk, 35% come by bike, the rest by car. How many students come to school by car? If twice as many students walk home as those going in a car, how many would this be? (assuming all who biked, bike home) 810 780
Lesson Objective To understand what a ratio is, and how it can be used in everyday situations Lesson Success Criteria • Can understand what a ratio is • Can simplify a ratio • Can rewrite a ratio as a fraction, and vice versia
So what are Ratios? A ratio is a comparison of like quantities. A ratio can be written as a fraction, or using a colon (:) between the quantities being compared. Example: 1:1 2:3
Other Important Info Ratios can compare 2 or more like quantities Quantities must be in the same unit if being compared Simplified ratios use whole numbers only Ratios can be simplified by division (equivalent ratios)
Example A baseball team plays 80 games in a season. It wins 60 games, and loses 20 games. The ratio of ‘wins’ to ‘games played’ is 60 : 80 or 3 : 4 The ratio of ‘loses’ to ‘games played’ is 20 : 80 or 1 : 4 The ratio of ‘wins’ to loses’ is 60 : 20 or 3 : 1
Example A jar has blue, red and yellow lollies in the ratio of 1:2:4. Find out how many of each, if there is a total of 280 lollies in the jar. A ratio of 1:2:4 means that for every blue lolly, there is 2 red lollies, and 4 yellow lollies. There is a total number of 7 parts (1+2+4). How many lots of 7 are there? 280/7 = 40. Multiply each part of the ratio by 40 gives us our final quantities. B:R:Y = 1:2:4 = 40:80:160 - note equivalent ratios!
Homework Chapter 3: Ratio Ex H, I: Pages 49-52