Ratios and Rates Test Study Guide

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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.

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What is a rate?

Back

A rate is a specific kind of ratio that compares two quantities with different units, such as speed (miles per hour) or price per item.

Front

How do you find the percentage of a number?

Back

To find the percentage of a number, multiply the number by the percentage (as a decimal). For example, to find 30% of 200, calculate 200 x 0.30 = 60.

Front

What is the unit rate?

Back

The unit rate is the quantity of one item per one unit of another item. For example, if a car travels 300 miles in 5 hours, the unit rate is 60 miles per hour.

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How do you calculate the total number of items from a percentage?

Back

To calculate the total number of items from a percentage, divide the part by the percentage (as a decimal). For example, if 30 is 20% of a number, the total is 30 ÷ 0.20 = 150.

Front

What is the formula for finding the discount amount?

Back

The discount amount can be found using the formula: Discount = Original Price x Discount Rate.

Front

How do you express a ratio in simplest form?

Back

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

Front

What does it mean if a ratio is 7:18?

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A ratio of 7:18 means that for every 7 parts of one quantity, there are 18 parts of another quantity.

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How do you convert a fraction to a percentage?

Back

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

Front

What is the relationship between ratios and proportions?

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A proportion states that two ratios are equal. For example, if a/b = c/d, then a:b is proportional to c:d.