Question

12. A road 3.5 m wide surrounds a circular plot whose circumference is 44 m. Find the cost of paving the
road at 20 per m². (Take ^r=22/7
​

Answer 1

Step-by-step explanation:

circumference of circular plot = 44 m

2πr = 44

$2\pi \: r = 44 \\ r = \frac{44 \times 7}{2 \times 22} \\ r = \frac{44 \times 7}{44} \\ r = 7$

inner radius is 7m

width of road = 3.5 m

outer radius = 7 + 3.5 = 10.5 m

area of road

$= \pi( {(r1)}^{2} - {(r2)}^{2} ) \\ = \frac{22}{7} ( {(10.5)}^{2} - {7}^{2} ) \\ = \frac{22}{7} (110.25 - 49) \\ = \frac{22}{7} \times 61.25 \\ = 22 \times 8.95 \\ = 196.9 \: sq \: m$

cost of paving road is Rs. 20 per sq m

= 196.9 × 20

= 3938

therefore the total cost for paving = Rs. 3938

hope you get your answer