A borrowed Rs.8000 from bank and returned Rs.4000 after 5 years. After 8 years from starting he returned Rs.6080 and settles his account. What was the rate of interest?

4%

Total interest paid = (₨.4000 + ₨.6080) - (₨.8000) = ₨.2080

Interest = interest on ₨.8000 for 5 years + interest on remaining ₨.4000 for 3 years

2080 = \(\frac{8000 × 5 ×R}{100}\) + \(\frac{4000 × 3 ×R}{100}\)

R = \(\frac{2080 × 100}{13 × 4000}\)

    = 4%