Area Problems The radius of a circle has been reduced from 9 cm to 7 cm . the appropriate percentage decrease in area is? 31.5 % 34.5 % 39.5 % 65.5 % 31.5 % 34.5 % 39.5 % 65.5 % ANSWER EXPLANATION DOWNLOAD EXAMIANS APP Original area = (22/7) x 9 x 9 cm2New area = (22/7) x 7 x 7 cm2? Decrease = 22/7 x [(9)2 -(7)2] cm2=(22/7) x 16 x 2 cm2Decrease percent = [(22/7 x 16 x 2) /( 7/22 x 9 x 9)] x 100 %= 39.5 %
Area Problems The length of a rectangle is twice its breadth. If its length is decreased by 5 cm and the breadth is increased by 5 cm, the area of the rectangle is increased by 75 cm 2 . Therefore , the length of the rectangle is? 50 cm 20 cm 30 cm 40 cm 50 cm 20 cm 30 cm 40 cm ANSWER EXPLANATION DOWNLOAD EXAMIANS APP Let breadth = b, length = 2b? Area of rectangle = 2b x b = 2b2As per question. ? (2b - 5 ) (b + 5 ) = 2b2 + 75? 5b = 75 + 25? 5b = 100? b = 100 / 5 = 20Hence, length of the rectangle =2b = 2 x 20 = 40 cm.
Area Problems A circular disc of area 0.49 ? square meters, rolls down a length of 1.76 km. The number of revolutions it makes is? 400 300 4000 600 400 300 4000 600 ANSWER EXPLANATION DOWNLOAD EXAMIANS APP Area = ?r2 = 0.49? ? r = 0.7 mNumber of revolutions = total distance / circumference = (1.76 x 1000) / (2 x 22/7 x 0.7) = 400
Area Problems The base of right-angled triangle is 5 meters and hypotenuse is 13 meters . Its area will be? 25m2 None of these 30m2 28 m2 25m2 None of these 30m2 28 m2 ANSWER EXPLANATION DOWNLOAD EXAMIANS APP Altitude = ?(13)2 - (5)2= ?144 = 12m ? Area of the triangle = (5 x 12 ) / 2 m2= 30m2
Area Problems If the sides of a rectangle are increased by 10% find the percentage increased in its diagonals. 18% 10% 15% 20% 18% 10% 15% 20% ANSWER EXPLANATION DOWNLOAD EXAMIANS APP According to the formula,? Percentage increase in sides = 10%? Percentage increase diagonals = 10%
Area Problems The circumference of a circle is 25 cm. Find the side of the square incribed in the circle. 29/??3 cm 21/??3 cm 25/??2 cm 23/??2 29/??3 cm 21/??3 cm 25/??2 cm 23/??2 ANSWER EXPLANATION DOWNLOAD EXAMIANS APP Circumference of the circle = 2?r = 25? r = 25 / (2?)According to the formula,Side of inscribed square = r?2 = 25 / (2?r x ?2) = 25 / (??2 ) cm
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