Setting Up Proportions

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What is a proportion?

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A proportion is an equation that states that two ratios are equal. For example, if a/b = c/d, then a, b, c, and d are in proportion.

Tags

CCSS.7.RP.A.2A

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How do you set up a proportion?

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To set up a proportion, identify two ratios that you want to compare and set them equal to each other. For example, if you know that 3/4 = x/8, you can set up the proportion.

Tags

CCSS.7.RP.A.2A

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What is cross-multiplication in proportions?

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Cross-multiplication is a method used to solve proportions. If a/b = c/d, then ad = bc.

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If 18 out of 30 students have an A, how do you find the total number of students earning an A in a class of 80?

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CCSS.7.RP.A.3

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How do you find the number of subscriptions sold over a different time period?

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CCSS.7.RP.A.2C

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If 16 out of 25 students are boys, how do you find the number of boys in a class of 40?

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CCSS.7.RP.A.2C

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How do you calculate the cost of hamburger meat based on a given price per weight?

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CCSS.6.RP.A.3B

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What is the relationship between cost and weight in a proportion?

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In a proportion involving cost and weight, you can set up a ratio of cost to weight and use it to find unknown values.

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CCSS.7.RP.A.2C

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How do you find the number of pounds of gummy bears you can buy for a certain amount of money?

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CCSS.6.RP.A.3B

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What does it mean if two ratios are equivalent?

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If two ratios are equivalent, it means they represent the same relationship between quantities, and their cross-products are equal.

Tags

CCSS.6.RP.A.3A