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Question 1 Four concentric circles are drawn with the radii at interval of X units. If the radius of inner circle is X units then the ratio of the area between the 4th and 3rd circles to the area between the 2nd and 1st circles is: a)1:2 b)2:1 c)4:3 d)7:3 Answer : d)7:3 Solution : Let X be the radius of inner(1st) circle. Given that the radii of the circles are at the intervals of X units. Then X + X = 2X, 2X + X = 3X, 3X + X = 4X are the radii of successive circles respectively. Now, the area of first circle = pi(X) 2 = pi x X 2 Area of second circle = pi(2X) 2 = 4 x pi x X 2 Area of third circle = pi(3X) 2 = 9 x pi x X 2 Area of fourth circle = pi(4X) 2 = 16 x pi x X 2 Then, the area between 1st and 2nd circles = (4 x pi x X 2 ) - (pi x X 2 ) = 3piX 2 br /> And the area between 3rd and 4th circles = (16 x pi x X 2 ) - (9 x pi x X 2 ) = 7piX 2 Therefore the required ratio = 7piX 2 / 3piX 2 = 7/3 Hence the answer is 7:3 Question 2 88 and 66 are ...