There are two cuboidal boxes as shown in the adjoining figure. Which box requires the lesser amount of material to make?

Solution

Total surface area of the cuboid (a) = 2[lb + bh + hl]
= 2 [(60 x 40) + (40 x 50) + (50 x 60)] cm²
= 2[2400 + 2000 + 3000] cm²
= 2[7400 cm²] = 14800 cm²
Total surface area of the cuboid (b) = 2[lb + hh + hl]
= 2[(50 x 50) + (50 x 50) + (50 x 50)]
= 2[2500 + 2500 + 2500] cm²
= 2 [ 7500 cm²] = 15000 cm²
Since the total surface area of the second (b) is true.
∴ Cuboid (a) will require lesser material.