Ratios/Rates/Percents

A ratio is a comparison of two quantities, showing how many times one value contains or is contained within the other.

Ratios can be written in three ways: using a colon (e.g., 4:3), as a fraction (e.g., 4/3), or with the word 'to' (e.g., 4 to 3).

A unit rate is a comparison of two different quantities when they are combined together, expressed as a quantity of one. For example, if you buy 5 pounds of apples for $10, the unit rate is $2 per pound.

To find the unit rate, divide the total quantity by the number of units. For example, if you spend $40 on 5 pounds of concrete, the unit rate is $40 ÷ 5 = $8 per pound.

A percent is a ratio that compares a number to 100. It is often used to express how much of something there is out of a total.

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%.

Ratios can be expressed as fractions. For example, the ratio 4:3 can be written as the fraction 4/3.

To compare two ratios, you can cross-multiply or convert them to fractions and find a common denominator.

A better buy is determined by comparing the unit prices of different products. The product with the lower unit price is the better buy.

The fraction of the counters that are green is 4/(4+5) = 4/9.