A sum of money becomes $\frac{768}{243}$ times of itself in 4 years. Find the rate of interest if compounded annually.

33.33 %

A = P (1+ $\frac{R}{100}$)⁴                            

$\frac{768}{243}$ = (1+ $\frac{R}{100}$)⁴      

$\frac{256}{81}$ = (1+ $\frac{R}{100}$)⁴

($\frac{4}{3}$)⁴ =   (1+ $\frac{R}{100}$)⁴

$\frac{1}{3}$ = $\frac{R}{100}$

R = $\frac{100}{3}$ = 33.33 %