Question

Cereal is packaged in a box shaped like a rectangular prism with a base 7.5 by 2 inches, and a height of 10 inches. Manufacturing each box requires 10% more cardboard than the box’s surface area. How much cardboard is needed to make each box

Answer 1

1.10*2*(7.5*2 + 10*(7.5+2)) = 242 . . . . square inches

The total area is 2(LW +H(L +W)). You want 10% more than that, so can find it by multiplying the area by 1.10.