Question

Find the number of coins 1.5cmin diameter and 0.2cm thick to be melted to form a right circular cylinder of height 10cm and diameter 10.5cm

Answer 1

coins are in the form of thin cylinder
Volume of each coin = π×(0.75)²×0.2 =0.1125π cm³

Volume of melted cylinder = π× (2.25)²× 10 = 50.625π cm³

number of coin required = (volume of melted
cylinder)/(volume of each coin)

                                 = 50.625π/0.1125π = 450 coins