Directions for questions 60 to 93: Answer the following questions independently.
A square tin sheet of side 12 inches is converted into a box with open top in the following steps.
The sheet is placed horizontally. Then, equal-sized squares, each of side x inches, are cut from the
four corners of the sheet. Finally, the four resulting sides are bent vertically upwards in the shape of
a box. If x is an integer, then what value of x maximizes the volume of the box?