the road 3.5m wide surrounds a circular plot whose circumference is 44m find the cost of paving the road at RS 20 per m. for 7 class
Answers
Step-by-step explanation:
Let the 'r' and 'R' be the radii of the inner and outer circle respectively.
Circumference of the circle = 44 m
2πr = 44
2*22/7*r = 44
r = (44*7)/44
r = 7 m
So, the radius of the inner circle is 7 m
Width of the road = 3.5 m
So, radius of the outer circle = 7 + 3.5 = 10.5 m
Area of the road = πR² - πr²
= 22/7*10.5*10.5 - 22/7*7*7
= 346.5 - 154
Area of the road = 192.5 sq m
Cost of paving the road = Rs. 50 per sq m
Total cost of paving the road = 192.5 × 20
Total cost = Rs. 3850
Step-by-step explanation:
Given,
circumference of plot = 44m
2πr = 44m
r = 7m
Radius of plot, r = 7m
Width of road = 3.5m
Radius of circle from centre of plot to the road, R = 7 + 3.5 = 10.5m
Area of road = π(R² - r²)
= 22/7 × 17.5 × 3.5
= 22/2 × 17.5
= 11 × 17.5
= 192.5m²
Cost of paving = ₹20 per m²
Total cost = 192.5 × 20
= ₹3850
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