The radius of a sphere is $3.5\, cm$. Find the cost of plating gold on its surface at the rate of ₹ $150$ per $cm^{2}$. (in ₹)

Find the radius of a sphere whose surface area is $154 \, cm^2$. (in $, cm$)

Find the curved surface area and the total surface area of a hemisphere with a radius of $17.5 \, cm$.

Find the surface area of a sphere of radius $7 \, cm$. (in $, cm^{2}$)

Find the surface area of a sphere with a diameter of $3.5 \, cm$. Assume $\pi = \frac{22}{7}$. (in $, cm^2$)

The radii of three out of four spheres are $33 \, cm$,$44 \, cm$,and $48 \, cm$ respectively. If the surface area of the fourth sphere is equal to the sum of the surface areas of the first three spheres,find the radius of the fourth sphere (in $cm$).