A cylindrical tank has a diameter of 16 feet and an altitude

A cylindrical tank has a diameter of 16 feet and an altitude of 5 feet.If a gallon of paint will cover 70 square feet, how many gallons are needed to cover the sides and top of the tank? Assume you cannot buy a fraction of a gallon.

Solution

dia = 16 ft

height = 5 ft

Surface area of cylidner = 2pi*r*h + 2pi*r^2

= 2pi(8*5) + 2pi(8)^2

= 208pi

= 653.45 sqft

Gallons of paint = surface are of cylider/area covered by 1 gallon paint

= 653.45/70 = 9.33 gallons

= 9 gallons