Question

A closed box is cuboid in shape with length = 40 cm, breadth = 30 cm and height = 50 cm. It is made of a thin metal sheet. Find the cost of metal sheet required to make 20 such boxes, if 1 m² of metal sheet costs Rs. 45.

Answer 1

Length of closed box (l) = 40 cm

Breadth (b) = 30 cm

and height (h) = 50 cm

Total surface area = 2 (lb + bh + hl)

= 2 (40 × 30 + 30 × 50 + 50 × 40) cm²

= 2 (1200 + 1500 + 2000) cm²

= 2 × 4700

= 9400 cm²

Surface area of sheet used for 20 such boxes = 9400 × 20 = 188000 cm²

∴ 188000 cm² = `(188000)/(100 xx 100) = 18.8 " m"^2`

Cost of 1 m² sheet = Rs. 45

Total cost = ₹ 18.8 × 45 = ₹ 846