Area Problems
The cost of cultivating a square field at the rate of Rs. 160 per hectare is Rs. 1440. the cost of putting a fence around it at 75 paisa per meter is?
Area = 1440 / 160 hectares = 9 hectares = 90000 m2? One side = ?90000 m = 300 mSo perimeter = 4 x 300 m = 1200 m ? Cost of fencing = Rs (1200 x 75) / 100= Rs. 900
Speed = 12 x (5/18) m/sec =10/3 m/sec there4; perimeter = (10/3) x 15 x 60 m=3000 m? 2( a + 4a) = 3000 m? a = 300 mSo, length = 1200 m and breadth = 300 m ? Area = (1200 x 300 ) m2 = 360000m2
Let breadth = b meters. then, length = 3b/2 meters ? b x 3b/2 = 2/3 X 10000? b2 = (4 x 10000)/9? b = ( 2 X 100)/3 m ? Length = (3/2) x (2/3) x 100 m= 100 m
Let original length = x and original breadth = y. Decrease in area = xy - ❨ 80 x x 90 y ❩ 100 100 = ❨ xy - 18 xy ❩ 25 = 7 xy. 25 ∴ Decrease % = ❨ 7 xy x 1 x 100 ❩% = 28%
Diameter of the circle = 13 + 5 = 18 cm? Radius = Diameter/2 =18/2 = 9 cm Area of the circle = ?r2 = (22/7) x 92 = (22 x 81)/9 = 1782/7 = 254.57 sq cm= 255 sq cm
EXAMIANS