Question 197328
concrete can be purchased by the cubic yard. how much will it cost to pour
 a circular slab 18 ft in diameter by 3 in. for a patio if the concrete
 costs $40.00 per cubic yard?
:
A circular concrete slab is a cylinder. Vol = {{{pi*r^2*h}}}
in this cylinder:
r = {{{18/2}}} = 9 ft
h = {{{3/12}}} = .25 ft
:
Find the volume in cu/ft:
V = {{{pi*9^2*.25}}}
V = 63.61725 cu/ft
:
Change to cubic yds; (1 cu/yd = 27 cu/ft) and multiply by $40:
Cost = {{{63.61725/27}}} * 40
Cost = $94.25
:
In practical terms, they may require you to buy 3 cu/yds, which is $120