what is the definishion of a unit rate

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it is a quantity divide by another quantiy.

examples miles/hr; days/week; kg/second; kg/meter; gram/mole; eggs/dozen; and so on. It is used to convert one unit to another, such as

dozen to eggs
feet to miles
miles to feet
seconds to kilograms.
seconds to hours

years to seconds.

A unit rate is a comparison of two different quantities, where one quantity is expressed as a single unit. It represents how much of one quantity corresponds to one unit of another quantity. In other words, a unit rate tells us how much of something there is for each unit of something else.

To find the unit rate, you need to divide the quantity you are interested in by the corresponding unit of the other quantity. For example, if you want to find the unit rate of speed (miles per hour), you would divide the total distance travelled (in miles) by the time taken to travel that distance (in hours).

Unit rates are useful in many real-life scenarios and are commonly used in various fields such as mathematics, science, finance, and everyday situations like shopping, cooking, and driving.