Final answer:
The cost of painting a closed circular oil tank is calculated by determining the tank's total outside surface area and multiplying by the cost per unit area, 60 rupees per dm^2. Without the tank's dimensions, we cannot provide a definitive answer.
Step-by-step explanation:
The cost of painting a closed circular oil tank is determined by finding the total outside surface area of the tank and then multiplying this area by the cost per square decimeter. To calculate the surface area of a closed circular oil tank, you need to find the area of the circular top and bottom (2 × π × radius^2) and the area of the cylindrical side (circumference × height or 2 × π × radius × height).
Once you have the total area in square decimeters, you multiply it by the cost per square decimeter (60 rupees) to arrive at the final cost. However, without the dimensions of the oil tank (radius and height), we cannot calculate the exact painting cost. Therefore, there is not enough information provided to answer the question definitively.