algebra word problem-flow rate?

Question

niagara falls has an avg of 212000 cubic ft of water passing over it each sec. is this rate more or less than 10 cubic ft per year?

i know i would have to convert using 1 cubic mile = 5280 cubic ft.
but after that, what's the next step? thanks for the help.

Answer 1

I think the original poster intended to ask whether it was more or less than 10 cubic miles per year.

1 mile = 5280 feet

1 square mile = 5280 * 5280 square feet

1 cubic mile = 5280 * 5280 * 5280 cubic feet

So 10 cubic miles is 10 * 5280 * 5280 * 5280 cubic feet

The flow in one year is 365 days/year * 24 hours/day * 60 minutes/hour * 60 seconds/minute * 212000 cubic feet / second
= 365 * 24 * 60 * 60 * 212000 cubic feet

The next step is to multiple those out (or eyeball them for order of magnitude) and compare. The flow looks to be about four and a half times larger.

Answer 2

Naturally it will be grater than 10 cubic ft per year