Solving Proportions

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What is a proportion?

Back

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.

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How do you solve a proportion?

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To solve a proportion, cross-multiply the terms. For example, for the proportion a/b = c/d, you can solve for a by using the equation a * d = b * c.

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What is the cross-multiplication method?

Back

The cross-multiplication method involves multiplying the numerator of one fraction by the denominator of the other fraction. This is used to solve proportions.

Front

If 3/4 = x/20, what is x?

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To find x, cross-multiply: 3 * 20 = 4 * x. Thus, x = 15.

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What is the definition of a ratio?

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A ratio is a comparison of two quantities by division. It can be expressed as a fraction, decimal, or percentage.

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How can you express a ratio in simplest form?

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To express a ratio in simplest form, divide both terms of the ratio by their greatest common divisor (GCD).

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What is a unit rate?

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A unit rate is a ratio that compares a quantity to one unit of another quantity. For example, if a car travels 300 miles in 5 hours, the unit rate is 60 miles per hour.

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If 5 pencils cost $2, what is the cost of 1 pencil?

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To find the cost of 1 pencil, divide the total cost by the number of pencils: $2 / 5 = $0.40 per pencil.

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What is the relationship between ratios and proportions?

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Ratios are comparisons of two quantities, while proportions are equations that show that two ratios are equivalent.

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If a recipe calls for 2 cups of flour for every 3 cups of sugar, what is the ratio of flour to sugar?

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The ratio of flour to sugar is 2:3.