Find the total surface area of a cone with diameter $6\, cm$ and slant height $11\, cm$. (in $cm^2$)

The slant height and base diameter of a conical tomb are $25 \, m$ and $14 \, m$ respectively. Find the cost of white-washing its curved surface at the rate of $Rs. 210$ per $100 \, m^2$.

Curved surface area of a cone $= \dots$

$A$ bus stop is barricaded from the remaining part of the road by using $50$ hollow cones made of recycled cardboard. Each cone has a base diameter of $40 \, cm$ and height $1 \, m$. If the outer side of each of the cones is to be painted and the cost of painting is $Rs. 12$ per $m^2$,what will be the cost of painting all these cones? (Use $\pi = 3.14$ and take $\sqrt{1.04} = 1.02$)

The total surface area of a cone is equal to:

$A$ heap of wheat is in the form of a cone whose diameter is $42 \, m$ and height is $20 \, m$. The heap is to be covered by canvas to protect it from rain. If the price of canvas is $₹ 75$ per $m^2$,find the cost of the canvas required.