Question 201229
Landsville has just finished building a new water tank. The tank is a cylinder with a cone on top. It has a diameter of 20 ft., a total height of 21 ft., and the cylindrical part is 15 ft. tall. The city decided to paint the whole outside (excluding the base or bottom). The paint costs $18 per gallon and only takes one coat. Each gallon covers approximately 250 sq. ft. How many gallons should the city buy?
---------------------------
For the cylinder:
{{{Area = pi*r^2*h}}}
{{{A = pi*100*15}}}
A = 1500pi sq feet = ~ 4712
------------------
For the cone:
{{{A = pi*r*sqrt(r^2+h^2)}}}
{{{A = pi*10*sqrt(100+36)}}}
A = ~ 336 sq ft
Total = ~ 5048 sq ft
--------------------
5184/250 = ~ 20.19 gallons --> 21 gallons