a certain sum becomes 4 times itself at simple interest in 8 years . in how many years does it become 10 times itself ?
Choose the correct choice
A) 24	B) 55	C) 77	D) 99	E) 01

Rationale: let the sum be rs . x , then it becomes rs . 4 x in eight years rs . 3 x is the interest on x for eight years . r = ( 100 * 3 x ) / ( x * 8 ) = 300 / 8 % if the sum becomes ten times itself , then interest is 9 x . the required time period = ( 100 * 9 x ) / ( x * 300 / 8 ) = ( 100 * 9 x * 8 ) / ( x * 300 ) = 24 years . answer : a
Answer: A