Nokea
You need to repaint a cylindrical water tank with a diameter of 2 meters and a height of 3 meters. Assuming one can of paint covers 10 sq m, how many cans do you need to cover only the exterior surface?
Correct Answer: C
Rationale: To find the surface area of the cylinder, calculate the lateral surface area using the formula 2πrh, where r is the radius (half of the diameter) and h is the height. Substituting the values, we get 2 * π * 1 * 3 = 6π square meters. Since each can covers 10 sq m, divide the total surface area by the coverage area per can: 6π / 10 ≈ 1.9 cans. Since you can't buy a fraction of a can, you would need to round up, so you would need 2 cans to cover the entire exterior surface. Therefore, you would need 2 * 6 = 12 cans in total. Choices A, B, and D are incorrect as they do not consider the correct surface area calculation or the rounding up to the nearest whole number of cans required.