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Question
The cost of fencing a circular field at the rate of Rs 25 per metre is Rs 5500. The field is to be ploughed at the rate of 50 paise per m2 . Find the cost of ploughing the field. [Take `π =22/7`].
Solution
Circumference`=("Total cost of fencing")/("Rate of fencing") = 5500/25 = 220`
Let the radius of the circle be r.
Now,
Circumference = 220
⇒ 2πr = 220
⇒ r = 35 cm
Now,
Area of field=`pi"r"^2 = 22/7xx(35)^2= 3850 "cm"`
Cost of ploughing = Rate ⨯ Area of field = 0.5 3850 = Rs 1925
Hence, the cost of ploughing the field is Rs 1925.
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