Barbara is packing a wedding gift that is contained within a rectangular box 20 by 18 by 4 in. How much wrapping paper will she require?
a. 512 in2
b. 1,440 in2
c. 1,024 in2
d. 92 in2
c. The surface area of the box is the add of the areas of all six sides. Two sides are 20 by 18 in or (20)(18) = 360 in2. Two sides are 18 by 4 in or (18)(4) = 72 in2. The last two sides are 20 by 4 in or (20)(4) = 80 in2. Adding up all six sides: 360 in2 + 360 in2 + 77 in2 + 77 in2 + 80 in2 + 80 in2 = 1,024 in2, is the total area. If you select a, you did not double all sides. If you select b, you determine the volume of the box.