 Hello and welcome to the session. Let's work out the following question. It says a cubical block of side 7 cm is surmounted by a Hemisphere. What is the greatest diameter the Hemisphere can have? Find the surface area of the solid. So let's now move on to the solution. We are given a cubical block with side 7 cm each and it is surmounted by a cubical block. Now since the Hemisphere is placed on the top of the cube of side 7 cm, the greatest diameter of the Hemisphere will be equal to the length of an edge of the cube rather 7 cm. So the greatest diameter of the Hemisphere would be 7 cm. Now the total surface area of the solid will be equal to the surface area of the cube plus curved surface area, the curved surface area of Hemisphere minus base area of the Hemisphere. That is the circular base of the Hemisphere. Now the surface area of cube is given by 6L square where L is the side. Therefore surface area of the cube will be 6 into 7 square that is 249. 49 into 6 is 294 cm square and the curved surface area of Hemisphere is equal to 2 pi r square. Now diameter of the Hemisphere is 7 cm therefore radius will be half of the diameter that is 7 by 2 cm. So now the curved surface area will be 2 into pi that is 22 by 7 into r is 7 by 2 cm and it comes out to be 77 cm square. Now base area of the Hemisphere is a circle. Area of the circle is pi r square t7 by 2 cm square. Now this is equal to 38.5 cm square. Therefore the total surface area of the solid will be 294 plus 77 minus 38.5 cm square. And it is equal to 332.5 cm square. Hence the required area is 332.5 cm square. So this completes the question and the session life for now. Take care. Have a good day.