The radii of two cylinders are in the ratio $3: 7$ and their heights are in the ratio $28: 15$. Calculate the ratio of their curved surface areas.

$A$ dome of a building is in the form of a hemisphere. From inside,it was white-washed at the cost of $Rs. 4989.60$. If the cost of white-washing is $Rs. 20$ per square metre,find the inside surface area of the dome. (in $, m^2$)

$A$ hemispherical bowl of radius $18\, cm$ is completely filled with medicine. This medicine is to be filled in cylindrical bottles of radius $2\, cm$ and height $4\, cm$. How many bottles are required to empty the bowl?

$A$ metal pipe is $77 \, cm$ long. The inner diameter of a cross section is $4 \, cm$ and the outer diameter is $4.4 \, cm$ (see Fig.). Find its total surface area. (in $, cm^2$)

The slant height of a cone is $25 \,cm$ and its curved surface area is $550 \,cm^{2}$. Find the radius,height,and the total surface area of the cone.

If the lateral surface area of a cylinder is $94.2 \, cm^2$ and its height is $5 \, cm$,then find the radius of its base. (in $, cm$)