Find the lateral surface area of the cuboid which measures $50 \, cm \times 40 \, cm \times 30 \, cm$. (in $cm^2$)

In a cylinder,if the radius is doubled and the height is halved,the curved surface area will be:

State whether the following statement is True or False and justify your answer: If the radius of a cylinder is doubled and its height is halved,the volume will be doubled.

Find the surface area of a sphere of radius $50\, cm$ $(\pi = 3.14)$ (in $cm^2$).

Write True or False and justify your answer in each of the following:
If the radius of a cylinder is doubled and its curved surface area is not changed,the height must be halved.

For a given cylinder,the diameter of the base is $7 \,cm$ and its height is $12 \,cm$. Find the curved surface area of a cylinder (in $cm^2$).