Question

a circular pool measures 12 feet across. one cubic yard of concrete is to be used to create a circular border of uniform width around the pool. if the border is to have a depth of 3inches, how wide will the border be? (1cubic yard=27cubic feet)

Answer 1

If the width is w inches, the volume of the border (in^3) is

pi((72+w)^2 - 72^2)*3 = 46656
w = 28.7