Find the surface area of a sphere of radius $30 \, cm$ $(\pi = 3.14)$ (in $cm^2$).

State whether the following statement is true or false:
An open box measuring $12\, cm \times 4\, cm \times 3\, cm$ can hold a bar of $15\, cm$ in length.

The ratio of the radius and slant height of a cone is $3:5$ and its curved surface area is $423.9 \, cm^2$. Find its volume. $(\pi = 3.14)$ (in $cm^3$)

If the edge of a cube is $12 \, cm$,find its volume (in $cm^3$).

In $\Delta ABC$,$\angle B = 90^{\circ}$,$AB = 6.3 \, cm$,and $BC = 8.4 \, cm$. If the triangle is revolved about the side $AB$,find the volume of the cone so obtained. Similarly,if the triangle $ABC$ is revolved about the side $BC$,find the volume of the cone so obtained.

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