One cubic metre of iron weighs 7.800 kg. The weight of iron in a pipe of length 4 m, whose interior and exterior diameters measure 10 cm and 12 cm respectively, is nearly

Floor of a room is $15 \text{ m } 17 \text{ cm}$ long and $9 \text{ m } 2 \text{ cm}$ broad. What is the least number of square tiles required to pave the floor?

A 30 meter deep well, with a diameter of 7 meters is dug and the earth from digging is evenly spread out to form a platform of size 22 meters by 14 meters. The height of the platform is:

If each side of a cube is decreased by $19 \%$, then the decrease in surface area is :

Two identical solid cubes of side 5 cm are joined end to end. Then the total surface area of the resulting cuboid is:

A pump can be operated both for filling a tank and for emptying it. The capacity of the tank is 2400 $m^{3}$. The emptying capacity of the pump is 10 $m^{3}$ per minute higher than its filling capacity. Consequently, the pump needs 8 minutes less to empty the tank as to fill it. The filling capacity of the pump is

Consider the following statements, which of them is/are correct?

A. If the height of cylinder is doubled, the area of curved surface is doubled.

B. If the radius of a hemispherical solid is doubled, its total surface area becomes fourfold.

C. If a hemisphere and cone have equal bases and equal heights, then the ratio of curved surface area is $\sqrt{2}:1$.