The curved surface area of a right circular cone of height $15\, cm$ and base diameter $16\, cm$ is..........$\pi\, cm^2$.

Consider the volumes of the following:
$1.$ $A$ parallelepiped of length $5\,cm$,breadth $3\,cm$ and height $4\,cm$.
$2.$ $A$ cube of each side $4\,cm$.
$3.$ $A$ cylinder of radius $3\,cm$ and length $3\,cm$.
$4.$ $A$ sphere of radius $3\,cm$.
The volumes of these in decreasing order are:

If the measured value of the radius is $1.5 \%$ larger,the percentage error (correct to one decimal place) made in calculating the volume of a sphere is

The radii of two cones are in the ratio $2:1,$ and their volumes are equal. Find the ratio of their heights.

The cross section of a canal is in the shape of an isosceles trapezium which is $4 \ m$ wide at the bottom and $5 \ m$ wide at the top. If the depth of the canal is $2 \ m$ and it is $120 \ m$ long,what is the maximum capacity of this canal? (in $m^3$)

The cost of paint is ₹ $36/kg$. If $1\, kg$ of paint covers $1.5\, m^2$,how much will it cost to paint the outside of a cube having a $2.5\, m$ side?