 Hello and welcome to the session. Today I will help you with the following question. The question says given a cylindrical tank in which situation will you find surface area and in which situation volume? a. to find how much it can hold b. number of cement bags required to plaster it c. to find the number of smaller tanks that can be filled with water from it. Amount of region occupied by a solid is called its volume and surface area of a solid is the sum of the areas of its faces. This is the key idea for this question. Let's see the solution now. Our first situation is to find how much it can hold. In this situation we must know how much of a substance can fill up the cylindrical tank. So by the definition of volume we say that it represents the amount of region occupied by a solid. Thus we need to find the volume of the tank in this case. The next situation is number of cement bags required to plaster it. In this situation the surfaces of the cylindrical tank need to be plastered by the cement. So to calculate the number of cement bags required we must know the surface area of the cylindrical tank. Since we already know that the surface area of a solid is the sum of the areas of its faces. Thus we need to find the surface area of the tank in this case. The next situation is to find the number of smaller tanks with water. In this situation we must know how much of a substance can fill up the cylindrical tank. So to calculate the number of... We need to find the total volume of water the tank can hold. We need to find the volume of the tank. Hence our final answer is for the A part its volume, B part its surface area and for the C part its volume. So hope you enjoyed this session. Have a good day.