Area Problems The ratio of the radii of two circle is 1:3 the radio of their areas is? 1:3 1:9 1:6 None of these 1:3 1:9 1:6 None of these ANSWER EXPLANATION DOWNLOAD EXAMIANS APP The Radio of areas = area of first circle : area of 2nd circle= ?r2 / ?(3r)2= ?r2/ 9 ?r2= 1/9 = 1: 9
Area Problems The area of circle inscribed in an equilateral triangle is 462 cm . The perimeter of the triangle is? 126 cms 72.6 cms 42 ? 3 cms 168 cms 126 cms 72.6 cms 42 ? 3 cms 168 cms ANSWER EXPLANATION DOWNLOAD EXAMIANS APP ? 22/7 x r2 = 462? r2 = (462 x 7) /22 = 147? r = 7?3 cm ? Height of the triangle = 3r = 21?3 cmNow, ? a2 = a2/4 + (3r)2? 3a2/4 = (21?3)2? a2 = (1323 x 4)/3? a = 21x 2 = 42 cm? Perimeter = 3a = 3 x 42=126 cm
Area Problems The ratio between the length and the breadth of a rectangular park is 3 : 2. If a man cycling along the boundary of the park at the speed of 12 km/hr completes one round in 8 minutes, then the area of the park (in sq. m) is: 15360 30720 307200 153600 15360 30720 307200 153600 ANSWER EXPLANATION DOWNLOAD EXAMIANS APP Perimeter = Distance covered in 8 min. = ❨ 12000 x 8 ❩m = 1600 m. 60 Let length = 3x metres and breadth = 2x metres. Then, 2(3x + 2x) = 1600 or x = 160. ∴ Length = 480 m and Breadth = 320 m. ∴ Area = (480 x 320) m2 = 153600 m2
Area Problems A hall 20 m long and 15 m broad is surrounded by a verandah of uniform width of 2.5 m. the cost of flooring the verandah at the rate of 3.50 per sq. meter is? Rs. 600 Rs. 700 Rs. 500 Rs. 800 Rs. 600 Rs. 700 Rs. 500 Rs. 800 ANSWER EXPLANATION DOWNLOAD EXAMIANS APP Area of verandah = [(25 x 20) -(20 x 15)] m2= 200 m2? Cost of flooring = Rs. (200 x 3.50)= Rs. 700
Area Problems A rectangle has 20 cm as its length and 200 sq cm as its area. If the area is increased by 1 1/ 5 time the original area by increase its length only then the perimeter of the rectangle so formed (in cm) is 72 60 68 64 72 60 68 64 ANSWER EXPLANATION DOWNLOAD EXAMIANS APP l1 = 20 cm, A1 = 200 sq cm? b1 = 200/20 = 10 cmNow, A2 = 200 x 6/5 = 240 sq cm b2 = 10 cm? l2 = 240/10 = 24 cm? Perimeter of new rectangle = 2(l2 + b2)= 2(24 + 10) = 2 x 34 = 68 cm
Area Problems A rectangular carpet has an area of 120 sq. m and a perimeter of 46 m . The length of its diagonal is? 20 m 16 m 15 m 17 m 20 m 16 m 15 m 17 m ANSWER EXPLANATION DOWNLOAD EXAMIANS APP Let length = a metres and breadth = b metres Then, 2(a+b)= 46 ? (a+b) =23 and ab =120 ? Diagonal = ?a2 + b2?(23)2-2 x 120?289 = 17 m
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