Math CentralQuandaries & Queries


Question from Traci:

I have a pool that is 24 ft round. I want to put a trim of 2 inch deep and 1 foot wide white rock around the outside. My problem is that here you can only purchase the rock in bags of either 0.5 cu ft or 1 cu ft.
How do I figure out how many bags i will need to do this right?

Do you mean 24 feet in perimeter? If so, the "mean perimeter" of the trim [measured halfway between the inside and the outside] will be pi feet longer (call it three). Volume will be about 27 x 1 x 2/12 which is 4.5 cubic feet, so four big bags & a small one should see you.

Interesting fact - this does NOT depend on the pool being circular. Exactly the same correction would work for any shape of pool provided only that it is one pool and does not have any islands.


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