an amount at compound interest sums to rs . 17640 / - in 2 years and to rs . 21168 / - in 3 years at the same rate of interest . find the rate percentage ?
"explanation : the difference of two successive amounts must be the simple interest in 1 year on the lower amount of money . s . i = 21168 / - - 17640 / - = rs . 3528 / - rate of interest = ( 3528 / 17640 ) × ( 100 / 1 ) = > 20 % answer : option e"
multiply(divide(subtract(21168, 17640), 17640), const_100)