 Hello and welcome to the session. The question says a hemispherical tank is made up of an iron sheet 1 cm thick. If the inner radius is 1 m then find the volume of iron used to make the tank. So first it is learned the formula to calculate the volume of hemispheres. This is equal to 2.3 pi r tube where r is the radius of the hemispheres and then to this formula we are going to solve the above problem. So this is our key idea. Now let's begin with the solution. Now we are given the thickness of the sheet is equal to 1 cm that is 1 upon 100 meters or 0.01 meters. Also we are given the inner radius is equal to 1 meters. So this implies outer radius the tank is equal to 1 meters plus 0.01 meters that is the thickness of the bowl and this gives 1.01 meters. If suppose let this be the bowl then this is the thickness of 1 cm. The inner radius is given to us as 1 meter and its thickness is 1 cm. So this implies the outer radius this whole is equal to the inner radius plus the thickness that is 1 meters plus 0.01 meters. Now let's proceed on further. We have to find the volume of iron used to make the tank. So we have to find the volume of iron used and that is equal to the volume of outer hemisphere minus the volume of inner hemisphere. The sheeted portion we have to find out and that we will get if we subtract the volume of inner hemisphere from the volume of outer hemisphere. Now let us denote the inner radius of the hemispherical tank by small r and the outer radius by capital R. So the volume of iron used can further be written as 2 upon 3 into pi capital R cube minus 2 upon 3 pi into small r cube. So this is the volume of the outer hemisphere and this is the volume of the inner hemisphere and this is further equal to 2 upon 3 pi capital R cube minus small r cube. Now substituting the values of r capital R small r and pi we have 2 upon 3 pi is given to us in the beginning of the exercise as 22 upon 7 into 1.01 whole cube minus 1 whole cube and this is equal to 2 upon 3 into 22 upon 7 into whole cube of 1.01 as 1.030301 minus 1 and this is further equal to 2 upon 3 into 22 upon 7 into 0.030301 and this is equal to 0.0634 meters cube approximately. Since the radius of the outer and the inner hemisphere are in meters and the volume is given by units cube hence the volume of the sheet used or the iron used in making the hemispherical tank as 0.0634 meter cube approximately. So this is our answer. Hope you have enjoyed it. Take care and have a good day.