Problem: an amount at compound interest sums to rs . 17640 / - in 2 years and to rs . 19404 / - in 3 years at the same rate of interest . find the rate percentage ?
Rationale: explanation : the difference of two successive amounts must be the simple interest in 1 year on the lower amount of money . s . i = 19404 / - - 17640 / - = rs . 1764 / - rate of interest = ( 1764 / 17640 ) × ( 100 / 1 ) = > 10 % answer : option d
annotated_formula: multiply(divide(subtract(19404, 17640), 17640), const_100)