We have: The 4-people pizza's area is: \(8^2\Pi=200,96\left(inch^2\right)\)

So each person can eat: \(\dfrac{200,96}{4}=50,24\left(inch^2\right)\)

=> 16 people eat: \(50,24.16=803,84\left(inch^2\right)\)

=> The suitalbe pizza has the diameter is: \(\sqrt{\dfrac{803,84}{3,14}}.2=32\left(inch\right)\)