Problem of the Week – Problem 3 Solution – February 5th, 2017

Solution to How Big Is Your Pizza?

Correct solutions were submitted by:  none submitted

Let P denote the radius of a large Pizza House pizza.  Let D denote the radius of a large Domingo’s pizza.  Let J denote the radius of a large Papa Jim’s pizza.

Then (pi)P² = 1.147 (pi)D² and P = J + 1/2.

We want to find the value of P when D = J so we can have a basis for comparison. If D = J, then substitution of P – 1/2 in for D in the first equation gives P² = 1.147(P-1/2)².  Solving for P shows that P is approximately 7.544 inches.  It follows that if the radius of a large Pizza House pizza is less than 7.544 inches then Domingo’s large pizza is bigger, but if P is greater than 7.544 inches then Papa Jim’s large pizza is bigger.