A certain sum of money becomes Rs.24000 in 3 years and it becomes Rs.27783 in 6 years. Find the rate of interest, if compounded annually.

5%

Let the Sum = P

P  →  3 years  →  24000  →  in next 3 years  →  27783

\(\frac{27783}{24000}\) = (1 + \(\frac{R}{100}\))³ 

\(\frac{9261}{8000}\) = (1 + \(\frac{R}{100}\))³ 

(\(\frac{21}{20}\))³ = (1 + \(\frac{R}{100}\))³ 

1 + \(\frac{1}{20}\) = 1 + \(\frac{R}{100}\)

⇒  \(\frac{1}{20}\) = \(\frac{R}{100}\)  ⇒  R = 5%