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Power Point shared with permission from. Ms. Gallacher James Workman Middle School of Technology and the Arts A note from Ms. Gallacher:. California Standards.
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Power Point shared with permission from Ms. Gallacher James Workman Middle School of Technology and the Arts A note from Ms. Gallacher:
California Standards MG1.3 Use measures expressed as rates (e.g., speed, density) and measures expressed as products (e.g., person-days) to solve problems; check the units of the solutions; and use dimensional analysis to check the reasonableness of the answer. Unit 9: Rates Objective: Finding Unit Rates Finding Unit Prices to Compare Costs
Notes A rate is a comparison of two quantities measured in different units. 90 3 Ratio: Read as “90 miles per 3 hours.” 90 miles 3 hours Rate:
90 3 The ratio can be simplified by dividing: Notes Unit rates are rates in which the second quantity is 1. 90 3 30 1 = 30 miles, 1 hour unit rate: or 30 mi/h
Check It Out! Example 1 Penelope can type 90 words in 2 minutes. How many words can she type in 1 minute? 90 words 2 minutes Write a rate. Divide to find words per minute. 90 words ÷ 2 2 minutes ÷ 2 45 words 1 minute = Penelope can type 45 words in one minute.
455 students 91 computers 468 students 91 computers 5 students 1 computer Example 2: Estimating Unit Rates Estimate each unit rate. 468 students to 91 computers Choose a number close to 468 that is divisible by 91. Divide to find students per computer. 468 students to 91 computers is approximately 5 students per computer.
595 players 85 soccer balls 583 players 85 soccer balls 7 players 1 soccer ball Check It Out! Example 3 Estimate each unit rate. 583 soccer players to 85 soccer balls. Choose a number close to 583 that is divisible by 85. Divide to find players per soccer ball. 583 soccer players to 85 soccer balls is approximately 7 players per soccer ball.
Practice • Estimate each unit rate • 121 students in 3 buses • $31.50 for 4 hours
Example 5: Finding Unit Prices to Compare Costs Pens can be purchased in a 5-pack for $1.95 or a 15-pack for $6.20. Which pack has the lower unit price? Divide the price by the number of pens. price for package number of pens $1.95 5 = = $0.39 price for package number of pens $6.20 15 = $0.41 The 5-pack for $1.95 has the lower unit price.
price for bottle number of ounces price for bottle number of ounces Check It Out! Example 6 John can buy a 24 oz bottle of ketchup for $2.19 or a 36 oz bottle for $3.79. Which bottle has the lower unit price? Divide the price by the number of ounces. $2.19 24 = $0.09 $3.79 36 = $0.11 The 24 oz jar for $2.19 has the lower unit price.
Lesson Quiz: Part I 1. Meka can make 6 bracelets per half hour. How many bracelets can she make per hour? 2. Sam counted 157 blue jays in the park. There are 5 bird feeders in the park. Approximately how many birds are there for each bird feeder? Estimate each unit rate. 3. $2.22 for 6 stamps 4. 8 heartbeats in 6 seconds 12 ≈ 150/5 ≈ 30 birds per bird feeder $0.37 per stamp 1.3 beats/s
Lesson Quiz: Part II Find each unit price. Then tell which has the lower unit price. 5. A half dozen carnations for $4.75 or a dozen for $9.24 6. 4 pens for $5.16 or a ten-pack for $12.90. a dozen They cost the same.