Question 499418
Constructing a Border around a Pool:
A pool in the shape of a circle measures 10 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 3 inches, how wide will the border be?
:
Convert 1 cu yd to cu ft: 3^3 = 27 cu/ft
Convert 3 in to .25 ft
Find the area of the circular border:
{{{27/.25}}} = 108 sq/ft
:
Find the area of the pool (radius = 5 ft)
{{{pi*5^2}}} = 78.54 sq/ft
then
108 + 78.54 = 186.54 sq/ft is the total area (pool and border)
let r = the overall radius
{{{pi*r^2}}} = 186.54
divide both sides by pi, results
r^2 = 59.38
r = {{{sqrt(59.38)}}}
r = 7.7 ft is overall area
subtract the radius of the pool
7.7 - 5 = 2.7 is the width of the concrete border