A sum of money at simple interest amounts to ₹1012 in 2\(\frac{1}{2}\) years while in 4 years it amounts to ₹1067.20. Find the rate of interest and the sum.

4%, 920

In 4 years amount  = 1067.2

In 2\(\frac{1}{2}\) years amount  = 1012

4 - 2\(\frac{1}{2}\) = 1.5,

In 1.5 years amount → 1067.2 - 1012 = 55.8

                                       in 1.5 years  → 55.8

                                        in 1 year      → 36.8

                                        in 2.5 years  → 92

                           Principle = 1012 - 92 = 920

                                   R% = \(\frac{36.8}{920}\) × 100 = 4%