Area Problems The area of a circular field is 13.86 hectares . The cost of fencing it at the rate of 20 paisa per meter is? Rs. 324 Rs. 264 Rs. 198 Rs. 277.20 Rs. 324 Rs. 264 Rs. 198 Rs. 277.20 ANSWER EXPLANATION DOWNLOAD EXAMIANS APP ? 22/7 x r2 = 13.86 x 10000? r2 = (13.86 x 10000 x 7) / 22? r = 210 m ? Circumference = [2 x (22/7) x 210 ] m = 1320 m Cost of fencing = Rs. (1320 x 20)/100= Rs . 264
Area Problems A circle and a square have same area. The ratio of the side of the square and the radius of the circle is? ?? : 1 ? : 1 1 : ? 1 : ?? ?? : 1 ? : 1 1 : ? 1 : ?? ANSWER EXPLANATION DOWNLOAD EXAMIANS APP ? Area of square = Area of circle ? x2 = ?r2? x/r = ?? = ? ? : 1
Area Problems The length of a rectangle is double while its breadth is halved. What is the percentage change in area? 75 50 No change None of these 75 50 No change None of these ANSWER EXPLANATION DOWNLOAD EXAMIANS APP Let length = l and breadth = bThen, area = lb New length = 2lAnd new breadth = b/2 ? New area = ( 2l ) x (b/2) = lbSo, there is no change in area .
Area Problems A triangle with three equal sides has its area equal to 3?3 sq cm . Find its perimeter . 6?3 cm 5?3 cm 2?3 cm 7?3 cm 6?3 cm 5?3 cm 2?3 cm 7?3 cm ANSWER EXPLANATION DOWNLOAD EXAMIANS APP According to the question,?3a2/4 = 3?3 [ side = a, and area = ?3a2/4] ? a2/4 = 3 ? a2 = 3 x 4 ? a = 2?3? Required perimeter = 3a =3 x 2?3 = 6?3 cm
Area Problems An error 2% in excess is made while measuring the side of a square. The percentage of error in the calculated area of the square is: 4% 2.02% 2% 4.04% 4% 2.02% 2% 4.04% ANSWER EXPLANATION DOWNLOAD EXAMIANS APP 100 cm is read as 102 cm. ∴ A1 = (100 x 100) cm2 and A2 (102 x 102) cm2. (A2 - A1) = [(102)2 - (100)2] = (102 + 100) x (102 - 100) = 404 cm2. ∴ Percentage error = ❨ 404 x 100 ❩% = 4.04%
Area Problems The wheel of an engine turns 350 times round its axle to cover a distance of 1.76 km. The diameter of the wheel is 9 cm ?3 cm 3?3 cm 3 cm 9 cm ?3 cm 3?3 cm 3 cm ANSWER EXPLANATION DOWNLOAD EXAMIANS APP Distance covered in 1 round = (Total Distance) / (Total round)= (1.76 x 1000)/350= 176/35 m ? 2?r = (1.76 x 100) / 35 cm2? = Diameter = 17600 x 7/22 x 35 = 160 cm
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