Surface Areas a...

If the radius of a sphere is doubled, what is the ratio of the volume of the first sphere to that of the second sphere?

The surface area of a $$10\ cm \times 4\ cm\times 6\ cm$$ brick is 

The area of the cardboard needed to make a box of size $$25\ cm\times 15\ cm\times 8\ cm$$ will be 

Volume of two spheres are in the ratio $$64 : 27$$. The ratio of their surface areas is:

The surface area of a sphere of radius $$7$$ cm is:

If the diameter of a sphere is d, then it's volume is

The ratio of the radii of two spheres is $$4:5$$. Find the ratio of their total surface areas is:

If the diameter of a sphere is 'd' then its volume is:

Find the ratio of the volume of sphere $$A$$ to sphere $$B$$, if the ratio of the surface area of sphere $$A$$ to the surface area of sphere $$B$$ is $$729:1$$. 

A hemispherical tank full of water is emptied by a pipe at the rate of $$\displaystyle {3}\frac{4}{7}$$ litres per second . How much time will it take to half empty the tank, if the tank is $$3$$ metres in diameter? (Take $$\pi = \dfrac{22}{7})$$