If the base radius of a cone is increased by $20 \%$ and its slant height is doubled,then by what percentage will the area of its curved surface increase?

If $64$ buckets of water are removed from a cubical-shaped water tank completely filled with water, $1/3$ of the tank remains filled with water. The length of each side of the tank is $1.2\, m$. Assuming that all buckets are of the same measure, then the volume (in $litres$) of water contained by each bucket is:

The radii of two solid iron spheres are $1 \, cm$ and $6 \, cm$ respectively. $A$ hollow sphere is made by melting the two spheres. If the external radius of the hollow sphere is $9 \, cm$,then its thickness (in $cm$) is

If the volumes of two cubes are in the ratio $27: 1$,the ratio of their edges is

$A$ rectangular water tank has dimensions $80\, m \times 40\, m$. Water flows into it through a pipe with an opening area of $40\, cm^{2}$ at a speed of $10\, km/hr$. By how much will the water level rise in the tank in half an hour (in $cm$)?

The radius of a cylinder is the same as that of a sphere. Their volumes are equal. The height of the cylinder is