Question

A road is 3.5m wide is surrounds a circular plot whose circumferernce is 44m.Find the cost paving the road at Rs.10 per m square

Answer 1

area of road=circumference*width
=44*3.5=154

cost=area of road*cost
=154*10
=1540 rupees

Answer 2

Hi !

r = radius of the inner circle
R = radius of outer circle

Circumference of the circle = 44 m

i.e.,

2πr = 44

2*22/7*r = 44

44/7 r = 44

r = 7 m

radius of the inner circle = 7 m
==================================
given ,

width of road = 3.5 m

Radius of the outer circle = r + width of road
= 7 + 3.5 = 10.5 m

Area of outer circle = πR²
= 22/7*10.5*10.5
= 346.5 m²

Are of inner circle = πr²
= 22/7*7*7
= 154 m²

Area of the road = πR² - πr²
= 346.5 - 154
= 192.5 m²


Cost of paving the road = Rs. 10 / m²

Total cost of paving the road = 192.5 × 10
= Rs. 1925

The answer is -> Rs 1925

Hope this helps you !