there are two concentric circles with radii 5 and 4 . if the radius of the outer circle is increased by 20 % and the radius of the inner circle decreased by 50 % , by what percent does the area between the circles increase ?
the area of a circle is pir ^ 2 , where r is the radius . the area of the big circle is 25 pi . the area of the small circle is 16 pi . the area a 1 between the circles is 9 pi . when the big circle ' s radius increases , the new area is 36 pi . when the small circle ' s radius decreases , the new area is 4 pi . the area a 2 between the circles is 32 pi . the ratio of a 2 / a 1 is 32 / 9 = 3.56 which is an increase of 256 % . the answer is c .
multiply(divide(subtract(subtract(power(multiply(5, divide(add(const_100, 20), const_100)), const_2), power(multiply(4, divide(subtract(const_100, 50), const_100)), const_2)), subtract(power(5, const_2), power(4, const_2))), subtract(power(5, const_2), power(4, const_2))), const_100)