A certain sum on simple interest becomes ₹49,600 in 3 years and ₹56,000 in 5 years. If the rate of interest had been 2%, more, then in how many years would the sum have doubled ?

10

On S.I. , a certain sum become Rs 49600 in 3 years and Rs 56000 in 5 years.

Total interest in 2 years= 56000-49600

                                  = Rs 6400

Total interest in 1 years= \(\frac{6400}{2}\) =Rs 3200

Total interest in 5 years= 3200× 5 = Rs 40000

∴ Rate % = \(\frac{3200}{40000}\)  ×  100

              = 8%

New Rate = 8+2 = 10%

so time Required = \(\frac{100}{10}\)

                         =10 years