if the simple interest on a certain sum of money for 7 years is one – fifth of the sum , then the rate of interest per annum is
"explanation : let the principal ( p ) be x then , simple interest ( si ) = x / 5 time ( t ) = 7 years rate of interest per annum ( r ) = ( 100 × si ) / pt = ( 100 × ( x / 5 ) / ( x × 7 ) = 20 / 7 = 2.85 % answer : option e"
divide(divide(const_100, add(const_1, const_4)), 7)