The Base of a Rectangular Box Is to Be Twice

Multiple Choice

The base of a rectangular box is to be twice as long as it is wide. The volume of the box is 750 cubic inches. The material for the top costs $0.21 per square inch and the material for the sides and bottom costs $0.06 per square inch. Find the dimensions that will make the cost a minimum. ​​

A) Dimensions are 15" by 10" by 4" (high) .
B) Dimensions are 22" by 44" by 4" (high) .
C) Dimensions are 5" by 10" by 15" (high) .
D) Dimensions are 15" by 30" by 5" (high) .
E) Dimensions are 4" by 8" by 22" (high) .