Surface area-I understand that the surface area of the whole oil drum = upper and lower circular surfaces+barrel surface area.

The surface area of an oil drum = 3.14 * 0.2 * 0.2 * 2+0.6 * 2 * 3.14 * 0.2.

Total area12 =12 (3.14 * 0.2 * 0.2 * 2+0.6 * 2 * 3.14 * 0.2).

Paint amount required =12 (3.14 * 0.2 * 0.2 * 2+0.6 * 2 * 3.14 * 0.2) * 0.5 = 6.