Question

A cylindrical carton of oatmeal with radius 3.5in is 9in tall. If all surfaces except the top are made of cardboard, how much cardboard is used to make the oatmeal carton? Round to the nearest square inch.

Answer 1

236 in2

Explanation:

To find how much cardboard is used, we need to find the surface area of the cylinder, minus the top surface.

The area of the base is:

A_base = pi*r^2

Where r is the radius of the base.

A_base = pi*(3.5)^2 = 38.4845 in2

The area of the side is calculated as:

A_side = 2*pi*r*h

Where h is the height of the cylinder.

A_side = 2*pi*3.5*9 = 197.9203 in2

So the total area we want is:

A_total = A_base + A_side = 38.4845 + 197.9203 = 236.4048 in2

Rounding to nearest square inch, we have A_total = 236 in2