$A$ monument has $50$ cylindrical pillars each of diameter $50\, cm$ and height $4\, m.$ What will be the labour charges for cleaning these pillars at the rate of $50$ $paise$ per $m^{2}?$ (in $Rs.$) (Use $\pi=3.14$)

$A$ right prism has a triangular base whose sides are $13\, cm, 20\, cm$ and $21\, cm$. If the altitude of the prism is $9\, cm$,then its volume is......$cm^3$

$A$ right circular cylinder having diameter $21\, cm$ and height $38\, cm$ is full of ice cream. The ice cream is to be filled in cones of height $12\, cm$ and diameter $7\, cm$ having a hemispherical shape on the top. The number of such cones to be filled with ice cream is

An iron cube of $10\, cm$ sides is hammered into a rectangular sheet of thickness $0.5\, cm$. If the sides of the sheet are in the ratio $1:5$, the sides (in $cm$) are:

If the height of a cone is doubled,then its volume is increased by (in $\%$)

$A$ large cube is formed from the material obtained by melting three smaller cubes of sides $3\, cm$,$4\, cm$,and $5\, cm$ respectively. What is the ratio of the total surface areas of the smaller cubes to the large cube?