If exactly 216 people sign up for a charter flight, Leisure World Travel Agency charges $32Dfperson. However, if more than 216 people sign up for the...

A rectangular box is to have a square base and a volume of 20ft3. If the material for the base costs $0.33 per square foot, the material for the sides costs $0.10 per square foot, and the material for the top costs $0.17 per square foot, determine the dimensions of the box that can be constructed at minimum cost.