A closed rectangular box has inner dimensions 90 cm by 80 cm by 70 cm. Calculate its capacity and the area of tin-foil needed to line its inner surface.

Given,

Inner length of rectangular box = 90 cm

Inner breadth of rectangular box = 80 cm

Inner height of rectangular box = 70 cm

We know that

Capacity of rectangular box = volume of rectangular box = l × b × h

= 90 × 80 × 70

= 504000 cm³.

Area of tin foil = Surface area of box = 2(lb + bh + lh)

= 2(90 × 80 + 80 × 70 + 90 × 70)

= 2(7200 + 5600 + 6300)

= 2 × 19100

= 38200 cm².

Hence, capacity of box = 504000 cm³ and area of tin-foil needed = 38200 cm².