Jan is making a 3-tier wedding cake for 300 guests. She will make the cake for $3 per serving with the following specifications:

-Each serving is 4 inch.3
-Each tier must be smaller than the tier below it.
-Each square tier is 4 in. tall with a side length of 16 in., 14 in., 12 in., 10 in., 8 in., or 6.in
What is the cost of the most economical 3-tier cake that will serve 300 people?

1 answer

so, we need to divide each tier into 1" square pieces.

we need a^2+b^2+c^2 >= 300
6^2 = 36
8^2 = 64
10^2 = 100
12^2 = 144
14^2 = 196
16^2 = 256

a b c sum
6 8 10 200
6 8 12 244
6 8 14 296
6 8 16 356
8 10 12 308
That's it. Any other combination will be way over 308 servings.

Not sure why $3/serving was specified, since the cost makes no difference in the choice. Now, if different size layers had different cost per serving, that would change things.