Cake question

Question

You creating a wedding cake. The cake is composed of 3 square prism tiers. The bottom tier has a length of 20 inches, the second tier has a length of 14 inches, the top tier has a length of 8 inches. Each tier has a height of 6 inches. The surface of the entire cake needs to be frosted. If each can of frosting covers 250 sq inches, how many cans do you need?

Answer 1

Michael, I hope I can still help!

 

The bottom tier is 20 x 20 x 20. We don't need icing on the bottom, but we need it on the 4 sides, so 20 x 20 x 4 =1600 square inches.

 

The top of the bottom tier is 20 x 20 for 400 square inches, but there is a 14 x 14 = 196 square inches that don't need frosting. 400 - 196 = 204 square inches.

 

The 2nd tier has four 196 square inch sides for 784 square inches.

 

The top of the second tier is 196 - 36 = 160 square inches.

 

All but the bottom of the top tier need frosting. 6 x 6 x 5 = 180 square inches.

 

1600 + 204 + 784 + 160 + 180 = 2928 square inches.

 

2928/250 = 11.7, so we need 12 cans.