A sum of ₹25600 is invested on simple interest partly at 7% per annum and the remaining at 9% per annum. The total interest at the end of 3 years is ₹5832. How much money(in ₹) was invested at 9% per annum?

7600

Principal = Rs 25600

Interest for 3 years= Rs 5832

Interest for 1 years = Rs  \(\frac{5832}{3}\ =  Rs 1944

Overall Rate of Interest = \(\frac{19944}{25600}\) × 100

                                      = 7.6% 

By alligation:-

                7                  9

                       7.6% 

( 9- 7.6)          :      ( 7.6-7 )

   1.4               :         0.6

   7                  :          3   

The sum invested on 9% = \(\frac{3}{10}\) × 25600

                                          = Rs 7600 ( approx)