Question

a road 3.5 m wide a circular plot whose circumference is 44 m.find the cost of paving the road at Rs.20 per meter sq.

Answer 1

$2\pi \times r \: = 44 \\ 2 \times \frac{22}{7} \times r \: = 44 \\ r = 7 \\ big \: radius = 7 + 3.5 = 10.5 \\ area \: to \: be \: paved \: = \pi( {10.5}^{2} - {7}^{2} ) \\ area = 192.5 \\ cost \: = 192.5 \times 20 = 3850$