Question

Which of the following is the most appropriate unit to describe the rate at which water flows over Niagara Falls?

A: Day per billion gallons, because the independent quantity is volume of water in billion gallons and dependent quantity is time in days

B: Billion gallons per day, because the independent quantity is volume of water in billion gallons and dependent quantity is time in days

C: Billion gallons per day, because the independent quantity is time in days and dependent quantity is volume of water in billion gallons

D: Day per billion gallons, because the independent quantity is time in days and dependent quantity is volume of water in billion gallons

Answer 1

Here "rate" refers to how much water in how much time, so eliminate A qnd D. Which sounds correct, B or C? The correct answer corresponds to
(quantity of water) / (period of time).

Answer 2

C) Billion gallons per day, because the independent quantity is time in days and dependent quantity is volume of water in billion gallons.

Hope this helps!!