(i) Total surface area of cuboid = 2(ℓb + bh + ℓh)
= 2 (42 × 30 + 30 × 20 + 20 × 42)
= 2 (1260 + 600 + 840)
= 2 × 2700
= 5400 cm2
Diameter of the cone = 14 cm
Radius of the cone = 14/2 = 7cm
Surface area of remaining part = 5400 + 550 – 154 = 5796 cm2
(ii) Dimensions of rectangular solids = (42 × 30 × 20) cm
volume = (42 × 30 × 20) = 25200 cm3
Radius of conical cavity (r) =7 cm
height (h) = 24 cm
Volume of remaining solid = (25200 - 1232) = 23968 cm3
(iii) Weight of material drilled out
=1232 × 7 g = 8624g = 8.624 kg