Stacey needs to buy some cardboard to build a box 10 inches long, 9 inches wide, and 7 inches high. If she purchases 500 square inches of cardboard, how much will be left over?
Georgia Milestones Grade 7 Mathematics Formula Sheet
The formula for finding the surface area of a rectangular box is 2lw + 2lh + 2wh, where l is the length, w is the width, and h is the height.
In this case, the surface area of the box would be:
2(10*9) + 2(10*7) + 2(9*7) = 180 + 140 + 126 = 446 square inches
Since Stacey purchased 500 square inches of cardboard, the amount left over would be:
500 - 446 = 54 square inches
Therefore, Stacey will have 54 square inches of cardboard left over.