Answer 1

External length of the closed box = 80 cm

External Breadth of the closed box = 75 cm

External Height of the closed box = 60 cm

External volume of the closed box = 80 x 75 x 60 = 360000 cm³

Internal length of the closed box = 80 – 4 = 76 cm

Internal Breadth of the closed box = 75 – 4 = 71 cm

Internal Height of the closed box = 60 – 4=56 cm

Internal volume of the closed box = 76 x 71 x 56 cm = 302176 cm³

Volume of wood required to make the closed box = 360000 – 302176 = 57824 cm³