The area of circular playground is $22176 {\mathrm{m}}^2$. Find the cost of fencing this ground at the rate of $₹50$ per metre.

The area of a circle inscribed in an equilateral triangle is $154 {\mathrm{cm}}^2$. Find the perimeter of the triangle.

A field is in the form of a circle. A fence is to be erected around the field. The cost of fencing would be $₹2640$ at the rate of $₹12$ per metre. The field is to be thoroughly ploughed at the cost of $₹0.50/{\mathrm{m}}^2$. What is the amount required to plough the field?

An archery target has three regions formed by three concentric circles as shown in figure If the diameters of the concentric circles are in the ratios $1 : 2 : 3$, then find the ratio of the areas of three regions