Sir how to do this question

A sum of money triples itself in 18 years under simple interest , what is the rate of interest Per annum ? a . 9% b. 9.09% c.11.11% d. 13% I solved the question but not abled to match with option

Answers (3)

Yeah bro I too solved and my answer not matched with answer. My answer is 16.66% But in key the answers is 11.1%

let the sum be p & interest rate be r then 3p = p + 18pr/100 2p = 18pr/100 p=9pr/100 100p = 9pr 9r=100 r=100/9 r=11.11 r% = 11.11%