Rates, Ratios, and Proportions

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What is a unit rate?

Back

A unit rate is a comparison of two different quantities where one of the quantities is expressed as a single unit. For example, if you buy 3 CDs for $41.91, the unit rate is the cost per CD.

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How do you calculate a unit rate?

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To calculate a unit rate, divide the total quantity by the number of units. For example, to find the unit rate of 395 miles in 5 hours, divide 395 by 5, which equals 79 miles per hour.

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What is a ratio?

Back

A ratio is a relationship between two numbers indicating how many times the first number contains the second. It can be expressed in various forms, such as a fraction, with a colon, or with the word 'to'.

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What is a proportion?

Back

A proportion is an equation that states that two ratios are equal. For example, if 1/2 = 2/4, then these two ratios are in proportion.

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How can you determine which option is a better buy?

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To determine which option is a better buy, compare the unit prices of each option. The option with the lower unit price is the better buy.

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If a recipe calls for 2 eggs to make 10 pancakes, how do you find the number of eggs needed for a different quantity?

Back

To find the number of eggs needed for a different quantity, set up a proportion based on the original recipe. For example, to make 40 pancakes, you can set up the proportion 2 eggs/10 pancakes = x eggs/40 pancakes and solve for x.

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What is the formula for finding a unit price?

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The formula for finding a unit price is: Unit Price = Total Price / Number of Units.

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How do you convert a ratio to a percentage?

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To convert a ratio to a percentage, divide the first number by the second number and then multiply by 100. For example, for the ratio 1:4, (1/4) * 100 = 25%.

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What is the difference between a rate and a ratio?

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A rate is a specific kind of ratio that compares two quantities with different units, such as miles per hour or cost per item. A ratio compares two quantities of the same kind.

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How do you solve a proportion?

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To solve a proportion, cross-multiply the two ratios and set them equal to each other. For example, if a/b = c/d, then ad = bc.