Area Problems In a triangle ABC, BC = 5 cm AC = 12 cm and AB = 13 cm. The length of a altitude drawn from B on AC is? 7 cm 5 cm 4 cm 6 cm 7 cm 5 cm 4 cm 6 cm ANSWER EXPLANATION DOWNLOAD EXAMIANS APP ? s= (13 + 5 + 12) / 2 cm = 15cms-a = 2 cm, s-b = 10 cm and s-c = 3 cm ? Area = ? (15 x 2 x 10 x 3 ) cm2= 30 cm2? (12 x h) / 2 = 30 ? h = 5 cm
Area Problems A tank is 25m long 12m wide and 6m deep. The cost of plastering its walls and bottom at 75 paise per sq m is Rs. 358 Rs. 558 Rs. 458 Rs. 258 Rs. 358 Rs. 558 Rs. 458 Rs. 258 ANSWER EXPLANATION DOWNLOAD EXAMIANS APP Area to be plastered = 2 l + b × h + l × b = 2 25 + 12 × 6 + 25 × 12 = 744 s q . m Cost of plastering = 744 × 75 100 = R s . 558
Area Problems The diameter of the driving wheel of a bus is 140 cm. How many revolution, per minute must the wheel make in order to keep a speed of 66 kmph ? 350 550 250 150 350 550 250 150 ANSWER EXPLANATION DOWNLOAD EXAMIANS APP Circumference = No.of revolutions * Distance covered Distance to be covered in 1 min. = (66 X1000)/60 m = 1100 m.Circumference of the wheel = 2 x (22/7) x 0.70 m = 4.4 m.Number of revolutions per min. =(1100/4.4) = 250.
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 64 72 68 60 64 72 68 60 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 The ratio of the area of the circumcircle and the incircle of a square is 1 : ?2 2 : 1 ?2 : 1 1 : 2 1 : ?2 2 : 1 ?2 : 1 1 : 2 ANSWER EXPLANATION DOWNLOAD EXAMIANS APP Ratio of the areas of the circumcircle and incircle of a square = [(Diagonal)2?] / [(Side)2?]= [(Side x ?2)2] / (Side)2 = 2/1 or 2 : 1
Area Problems The ratio between the perimeter and the breadth of a rectangle is 5 : 1. If the area of the rectangle is 216 sq. cm, what is the length of the rectangle? 24 cm 18 cm None of these Data inadequate 24 cm 18 cm None of these Data inadequate ANSWER EXPLANATION DOWNLOAD EXAMIANS APP 2(l + b) = 5 b 1 ⟹ 2l + 2b = 5b ⟹ 3b = 2l b = 2 l 3 Then, Area = 216 cm2 ⟹ l x b = 216 ⟹l x 2 l = 216 3 ⟹ l2 = 324 ⟹ l = 18 cm
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