a cylindrical carton of oatmeal with radius 3.5 in. is 9 in. tall. all cardboard, how much cardboard is used to make the oatmeal carton?

Question

assume no surfaces overlap. round to the nearest square inch.

 

Answer 1

Let r = the radius of the cylinder and h = its height

• Area of the top + bottom surfaces of the cylinder = 2*pi*r²
• Area of the lateral surface (lateral area) = 2*pi*r*h

• Total Surface Area = 2*pi*r² + 2*pi*r*h = 2*pi*r*(r + h)

 

For r = 3.5 in. and h = 9 in.

• Total Surface Area = 2*3.14*3.5*(3.5 + 9) ≅ 275 in² (rounded to nearest square inch)