1. **State the problem:** We have a cylindrical tank with diameter 12 ft and height 2.5 m. We need to find: a) Number of metallic pieces (8 ft by 4 ft) to make the tank. b) Total cost of these pieces at 80000 each. c) Whether to use jerrycans or tins for painting the outside excluding the bottom, based on cost and coverage. 2. **Convert height to consistent units:** Height is 2.5 m. Since diameter is in feet, convert height to feet: $$2.5 \text{ m} \times 3.28084 = 8.2021 \text{ ft}$$ 3. **Calculate surface area of the tank excluding bottom:** The tank is a cylinder, so lateral surface area (side) is: $$A = 2 \pi r h$$ Radius $r = \frac{12}{2} = 6$ ft, height $h = 8.2021$ ft $$A = 2 \times \pi \times 6 \times 8.2021 = 2 \times 3.1416 \times 6 \times 8.2021 = 309.0 \text{ ft}^2$$ 4. **Calculate number of metallic pieces needed:** Each piece covers $8 \times 4 = 32$ ft$^2$ Number of pieces: $$\frac{309.0}{32} = 9.65625$$ Since pieces must be whole, round up: $$10 \text{ pieces}$$ 5. **Calculate total cost of pieces:** Each piece costs 80000 $$10 \times 80000 = 800000$$ 6. **Calculate paint needed and cost for jerrycans:** Coverage per jerrycan = 300 ft$^2$ Number of jerrycans: $$\frac{309.0}{300} = 1.03$$ Round up to 2 jerrycans Cost: $$2 \times 23000 = 46000$$ 7. **Calculate paint needed and cost for tins:** Coverage per tin = 200 ft$^2$ Number of tins: $$\frac{309.0}{200} = 1.545$$ Round up to 2 tins Cost: $$2 \times 14000 = 28000$$ 8. **Conclusion:** Tins cost 28000, jerrycans cost 46000. Tins are cheaper and sufficient. **Final answers:** - Number of pieces: 10 - Cost of pieces: 800000 - Use paint tins because they are cheaper (28000 vs 46000) and cover the area needed.