A field is in the form of a circle. A fence is to be erected around the field. The cost of fencing would be Rs. 2640 at the rate of Rs. 12 per metre. Then, the field is to be thoroughly ploughed at the cost of Re. `0. 50\ p e r\ m^2` . What is the amount required to plough the field? `[T a k e\ \ pi=22//7]` .