 Hello and welcome to the session. My name is Mansi and I am going to help you with the following question. The question says, the front compound wall of a house is decorated by wooden spheres of diameter 21 cm. Placed on small supports are shown in figure. Eight such spheres are used for this purpose and are to be painted silver. Each support is a cylinder of radius 1.5 cm and height 7 cm and is to be painted black. Find the cost of paint required if silver paint cost 25 paisa per cm square and black paint cost 5 paisa per cm square. So this is figure given to us in the question. Let us start with a solution to this question. Clearly we have to subtract the part of the sphere that is resting on the sphere while calculating the cost of silver paint. First of all we see that surface area r square minus equal to 21 by 2 r is equal to 1.5 cm. So something like this is in the question that the diameter is 21 cm so radius will be 21 by 2 cm and also it is given that each support is on a cylinder of radius 1.5 cm that is resting will have a radius of 1.5 cm and so small r becomes 1.5 cm and capital r is 21 by 2 cm. So we simply put in the values here and we get 1 by 4 because square of 21 is 441 minus minus 2.25 is 438 paisa that means for 1 cm square it is 25 paisa 5 by 100. Now we divide this by 100 to calculate this we get h where r is the radius of the cylinder and height of the cylinder that is equal to 8 into 2 into 22 by 7 into 1.5 that is the radius into 7 that is the height. That is equal to 5 cm square in the terms of rupees it will be 26.40. Therefore we can say that the question and enjoyed the session. Have a good day.