A sum of money becomes \(\frac{7}{6}\) of itself in 3 years at a certain rate of simple interest. What is the rate per annum?

Given: Amount becomes $\frac{7}{6}$ of principal in 3 years

So, interest earned =
$\frac{7}{6}P - P = \frac{1}{6}P$

Using simple interest formula:
$SI = \frac{P \times R \times T}{100}$

$\frac{P \times R \times 3}{100} = \frac{1}{6}P$

Cancel $P$:

$\frac{3R}{100} = \frac{1}{6}$

$R = \frac{100}{18} = \frac{50}{9} = 5\frac{5}{9}%$

Final Answer: $5\frac{5}{9}%$