1. Problem statement: We need to decide when to use surface area and when to use volume for a cylindrical tank in different situations. 2. Definitions: - Surface area of a cylinder is the total area that covers the outside, useful for coating or plastering. - Volume of a cylinder is the amount of space inside, useful for holding or storing substances. 3. Situation (a): To find how much the tank can hold. - Here, we want the capacity inside the tank. - Use volume, calculated by $$V=\pi r^2 h$$ where $r$ is radius and $h$ is height. 4. Situation (b): Number of cement bags required to plaster the tank. - Plastering covers the outside surface of the tank. - Use surface area, calculated by $$A=2\pi r h + 2\pi r^2$$ which is curved surface plus two circular ends. 5. Situation (c): To find the number of smaller tanks that the big tank can fill with water. - This relates to how much water fits inside. - Use volume of the big tank divided by volume of the smaller tank. Final answers: (a) Use volume to find capacity. (b) Use surface area to find plastering material. (c) Use volume to compare capacities.