19. A field is in the form of a cir...
Question

19. A field is in the form of a circle. The cost of plough the field at 1.50 per m’ is 5775. The cost of fencing the field at 8.50 per m is (1) * 1870 (2) 2870 (3) 1970 (4) 2970

11th - 12th Class
Maths
Solution
123
4.0 (1 ratings)
19. (1) Area of the field ( =frac{text { Total cost of ploughing }}{text { Rate per square metre }} ) ( =frac{5775}{1.50}=3850 mathrm{m}^{2} ) Let radius be ( r ). Then, ( pi r^{2}=3850 ) ( Rightarrow quad r^{2}=frac{3850}{pi}=frac{3850}{22} times 7=1225 ) ( Rightarrow quad r=sqrt{1225}=35 ) ( therefore ) Circumference of the field ( =2 pi r ) ( =2 times frac{22}{7} times 35=220 mathrm{m} ) ( therefore ) Cost of fencing the field ( =220 times frac{17}{2}=₹ 1870 )