Question

the cost of fencing a rectangular field at rs 10 per metre is rs 2200 if the length of the field is 20m then its perimeter is

Answer 1

Length of the fence = perimeter of the circle = 2πr where r is the radius

Cost of the fencing at Rs. 16 per metre= Rs. 5632
2πr × 16 = 5632
πr = 176
227227 × r = 176
r = 176×722176×722 = 56 metre

Area of the path = area of the outer circle - area of the  inner circle
= π(r+4)2 - πr2 =π(r2+ 8r + 16 - r2)
=π(8r + 16) =8π(r + 2)
= 8×22×5878×22×587 square meter

Required cost = Area × 21 = 8×22×58×2178×22×58×217 = 8 × 22 × 58 × 3 = Rs. 30624