Question

Bob's Barricades rents orange plastic cones to use as barricades in road construction. Each cone is 24 inches high with a diameter of 14 inches. A gallon of orange paint will cover approximately 400 square feet. About how many whole gallons of paint will Barb need to paint the lateral sides only of the 300 cones.

Answer 1

I will assume that we paint only the lateral surface of each cone
SA = πrs, where s is the slant height

http://math.about.com/od/formulas/ss/surfaceareavol_2.htm

so s^2 = 7^2 + 24^2
s = √625 = 25

So each cone has a lateral SA of π(7)(25) or 175π inches^2
300 cones have 52500π inch^2
number of gallons of paint
= 52500π/400
=412.33
but we can't buy a partial gallon, so
413 gallons are needed

check my arithmetic

Answer 2

It is 3 gallons