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Write Proportions. Sue needs 9 cups of flour to make 16 batches of cookies. How much flour does she need if she only wants to make a fourth of her recipe.

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Presentation on theme: "Write Proportions. Sue needs 9 cups of flour to make 16 batches of cookies. How much flour does she need if she only wants to make a fourth of her recipe."— Presentation transcript:

1 Write Proportions

2 Sue needs 9 cups of flour to make 16 batches of cookies. How much flour does she need if she only wants to make a fourth of her recipe. Set up proportion. Cross Multiply. Divide = cups Cups 9 16 X X batches 4 9 X 4 = ÷ 16 = = Cups Determine Ratios. EX 5)

3 Ralph has a paper clip with a mass of 9g and a volume of 3cm 3. What is the density? Set up proportion. Cross Multiply. Divide = Mass mass 9 g 3 cm 3 X 1 Volume cm 3 9 X 1 = 9 9 ÷ 3 = Determine Ratios. EX 6) Density – is a comparison of how much mass is in a unit of volume. Written – mass / unit volume 3 Density = 3g/cm 3

4 A 12 oz sport drink cost $1.08 and a 16 oz. sport drink cost $1.28. Which drink is the better buy? Step 2: set up proportion = Step 1: highlight rates oz $ $ X 1 Step 3: Cross multiply and divide EX. 7) Since you are comparing you will set up two proportions = oz $ X 1 $ Solve

5 oz drink that cost $1.08 is $0.09 / oz $1.08 X 1 = 1.08÷ Back 16 oz drink that cost $1.28 is $0.08 / oz $1.28 X 1 = 1.28÷ The better buy is the cheaper drink The 16 oz is the better buy

6 A car travels 480 miles in 8 hours and uses 16 gallons of gas. What is the average speed? ( miles per hour) What is the average gas mileage? ( miles per gallon) Try this on your own

7 Notes start here

8 Solve Proportions

9 CROSS PRODUCT RULE In the proportion =, the cross products, a · d and b · c are equal. abab cdcd EX 1) = uses 1. EX 2) = EX 3)

10 You can use the cross product rule to solve proportions with variables. Which help you find missing values. = = = m5m This is called the extreme and means ratio. = EX 4)

11 How many miles traveled per hour? miles Unit rate : a rate whose denominator is 1. It may not always look like a number; watch for words like per or each. EX 5) 200 / 4 hours Step 2: = Step 1: Step 3:

12 gallons miles EX 6) 160 / 5 How many miles per gallon? =

13 Convert 5,000 pounds to tons. 1: Set up = pounds tons = = EX 7) 2: _____ Proportion  C  D Convert 24 pints to cups. = cups pints = = EX 8)

14 Sue needs 9 cups of flour to make 16 batches of cookies. How much flour does she need if she only wants to make a fourth of her recipe. = EX 9)

15 Ralph has a paper clip with a mass of 9g and a volume of 3cm 3. What is the density? = EX 10) Density – is a comparison of how much mass is in a unit of volume. Written – mass / unit volume

16 A 12 oz sport drink cost $1.08 and a 16 oz. sport drink cost $1.28. Which drink is the better buy? = EX 11) =

17 A car travels 480 miles in 8 hours and uses 16 gallons of gas. What is the average speed? ( miles per hour) What is the average gas mileage? ( miles per gallon) Try this on your own


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