Time Value of Money

The rate of interest on a sum of money is $8\%$ p.a. for the first year, $6\%$ p.a. for the next 4 years and $4\%$ p.a. for the period beyond 5 years. If the simple interest accursed by the sum for a total period of 11 years is $\mathit{₹}1120$ what is the sum?