Final answer:
Ratios compare quantities and can be expressed as fractions or with a colon or 'to'. Rates compare measurements, where one has a value of 1. Unit rates express a measurement per unit of another. Unit scales compare actual dimensions to dimensions in a scale drawing or model, without requiring either value to be 1.
Step-by-step explanation:
Ratios compare two quantities and can be written as fractions, with a colon, or with the word 'to'. For example, the ratios 2/3, 2:3, and '2 to 3' all compare two numbers. Rates are a type of ratio that compare two measurements, where one of the measurements has a value of 1. Unit rates, such as 55 miles per hour (55 miles/1 hour), compare two measurements and express the value of one measurement per unit of another. Unit scales are ratios that compare the dimensions of an actual object to the dimensions represented in a scale drawing or model. Unit scales do not require either value to be 1. For example, a map's unit scale may be 1 inch = 100 feet.