 Hello and welcome to the session. My name is Asha and I am going to help you with the following question which says the inner diameter of a circular well is 3.5 meters. It is 10 meters deep. Find its inner curved surface area and second the cost of plastering this curved surface at the rate of rupees 40 per meter square. Let's begin with the solution and here we are given the inner diameter of the well is equal to 3.5 meters. Therefore inner radius of the well let us denote it by small r is equal to 3.5 meters divided by 2 and this gives 35.20 removing the decimal sign which further gives 7.4 meters. Also we are given that the depth of the well denoting it by h is equal to 10 meters. Now first we have to calculate the inner curved surface area and to calculate the inner curved surface area of a cylinder this formula is 2 pi r h where r is the radius and h is the height. So substituting the values of inner radius of the well and the depth of the well we get the inner curved surface area of the well. So this is equal to 2 into 22 upon 7 into radius is 7 upon 4 into height is 10. Now in simplifying it 7 cancels out with 7, 2 2's are 4, 2 1's are 2, 2 11's are 22 therefore we have 110 meters square. Therefore inner curved surface area is 110 meters square. Now proceeding on to the second part where we have to find the cost of plastering this curved surface at the rate of rupees 40 per meter square. Now the cost of plastering 1 meter square is equal to rupees 40 therefore cost of plastering 110 meters square is equal to rupees 40 into 110. This gives rupees 4400. Therefore our answer is the inner curved surface area of the well is 110 meters square and the cost of plastering the well from inside at the rate of rupees 40 per meter square is rupees 4400. So this completes the session. Bye and take care.