Compound interest earned after 2 years is Rs.3200 and simple interest earned after 3 years is Rs.4200 on a certain sum of money at a certain rate of interest. Find the sum.

Rs. 4900 Rs. 5600 Rs. 6300 Rs. 8000

Rs. 4900

S.I. of 3 years = Rs.4200 S.I. of 1 year = Rs.1400 ATQ, ⇒ R = \(\frac{400}{1400}\) = \(\frac{2}{7}\) ⇒ Principal × \(\frac{2}{7}\) = 1400 ⇒ Principal = 1400 × \(\frac{7}{2}\) = Rs.4900/-