What some ways that unit-rate are useful?

Answer 1

Unit rates are great for comparisons. For example: you want to buy some item - say, noodles - and you see two offers: (a) 2 kilograms for 10 dollars, and (b) 5 kilograms for 23 dollars. To compare which offer is more favorable, divide the number of dollars by the amount (in kilograms) for both; that gives you the price per kilogram. While there are exceptions, it is usually better to buy the item that costs less dollars per kilogram.