In how many years will Rs. 1,60,000 become Rs. 2,79,841 at a compound interest (Compounded annually) rate of 15% per annum?

Correct option is D

​$$A = P \left(1 + \frac{r}{100}\right)^{t}\\279841 = 160000\left(1 + \frac{15}{100}\right)^{t}\\\frac{279841}{160000}= \left(1 + \frac{15}{100}\right)^{t}\\ \left( \frac{23}{20}\right)^{4} = \left( \frac{23}{20}\right)^{t}\\t= 4$$​​