Study Guide: Ratios, Unit Rates, and Percents

Front

What is a ratio?

Back

A ratio is a comparison of two quantities that shows the relative size of one quantity to another, often expressed as 'a to b' or a:b.

Front

How do you calculate a unit rate?

Back

To calculate a unit rate, divide the quantity by the number of units. For example, if you run 100 yards in 20 seconds, the unit rate is 100 yards ÷ 20 seconds = 5 yards/second.

Front

What is a percent?

Back

A percent is a way of expressing a number as a fraction of 100. It is denoted using the symbol '%'. For example, 75% means 75 out of 100.

Front

How do you find 75% of a price?

Back

To find 75% of a price, multiply the price by 0.75. For example, for an armchair costing $240, 75% is $240 × 0.75 = $180.

Front

What does it mean if 20% of students are absent?

Back

If 20% of students are absent, it means that out of every 100 students, 20 are not present. For example, if there are 80 students, 20% absent means 16 students are out.

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How do you convert a fraction to a percent?

Back

To convert a fraction to a percent, divide the numerator by the denominator and then multiply by 100. For example, 1/4 = (1 ÷ 4) × 100 = 25%.

Front

What is the formula for finding a unit rate?

Back

The formula for finding a unit rate is: Unit Rate = Total Quantity ÷ Total Units.

Front

If a recipe calls for a ratio of 2:3 for sugar to flour, how much flour is needed for 4 cups of sugar?

Back

If the ratio is 2:3, for every 2 cups of sugar, you need 3 cups of flour. For 4 cups of sugar, you need (4 cups sugar × 3 cups flour) ÷ 2 cups sugar = 6 cups of flour.

Front

What is the relationship between ratios and proportions?

Back

Ratios compare two quantities, while proportions state that two ratios are equal. For example, if 1:2 = 2:4, then the ratios are proportional.

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How do you find the missing value in a ratio table?

Back

To find the missing value in a ratio table, set up a proportion using the known values and solve for the unknown.