What is time rates?

Answer 1

A rate is often the proportion of two quantities where the second quantity is one unit of measure. Kilometres (or miles) per hour would be a [time] rate of displacement - otherwise known as speed. But there are many rates where the denominators is not time. Litres per kilometre, as a measure of fuel consumption for vehicles or miles per gallon for fuel efficiency for cars, or grams per square metres for paper are all examples of such rates. Sometimes the variable of interest is a function of several variables - one of them being time. For example, total interest is a function of the amount borrowed, the interest rate and the time. Where the context does not make it clear, the phrase "time rate" is used to define which variable is the denominator.