In what time will ₹15625 amount to ₹17576 at 4% per annum compound interest?

Let the time be n years.

$A = P\Big(1 + \dfrac{r}{100}\Big)^n.$

Substituting values we get,

$\Rightarrow 17576 = 15625\Big(1 + \dfrac{4}{100}\Big)^n \\[1em] \Rightarrow 17576 = 15625\Big(\dfrac{104}{100}\Big)^n \\[1em] \Rightarrow \dfrac{17576}{15625} = \Big(\dfrac{26}{25}\Big)^n \\[1em] \Rightarrow \Big(\dfrac{26}{25}\Big)^3 = \Big(\dfrac{26}{25}\Big)^n \\[1em] \Rightarrow n = 3 \text{ years}.$

Hence, ₹15625 will amount to ₹17576 in 3 years at 4% per annum compound interest.