 Hello and welcome to the session. Let us discuss the following question. It says the radius of a spherical balloon increases from 7 centimeter to 14 centimeter as air is being pumped into it. Find the ratio of the surface areas of the balloon in the two cases. Now to find the ratio of the surface areas of the balloon in two cases, we'll first find the surface area when radius is 7 centimeter and then we'll find the surface area of the balloon when radius is 14 centimeter and then we'll find the ratio. For that, let us first know the formula for the surface area of a sphere because balloon is in the shape of sphere. The formula is 4 pi r square where r is the radius and value of pi is 22 upon 7. So this knowledge is the key idea. Let us now move on to the solution. We first find the surface area of balloon when radius is 7 centimeter. Now the surface area is 4 pi r square and r here is 7 centimeter and since the unit of radius is centimeter, so the unit of surface area will be centimeter square, now substitute the value of pi. It is 22 upon 7 into 7 into 7. 7 square is 7 into 7. 22 into 4 into 7 is 616 centimeter square. Now we find the surface area of the balloon when radius is 14 centimeter. It is 4 pi into 14 square. Now the value of pi is 22 upon 7. So the surface area is 4 into 22 upon 7 into 14 into 14. This is equal to 2464 centimeters square. Now we have to find the ratio of the surface areas in two cases. The ratio of surface areas is equal to 616 is to 2464 which is equal to 616 upon 2464 and this is equal to 1 upon 4 and the ratio is 1 is to 4. Hence the ratio is 1 is to 4. So this completes the question. Bye for now. Take care. Have a good day.