How much time will it take a principal of ₹640 to yield ₹768 as an amount at 2.5% simple interest per annum?

10 years 8 years 9 years 11 years

8 years

Total SI of ' t ' years = 768 - 640 = 128 Simple Interest = \(\frac{Principal ×Rate × Time }{100}\) 128  = \(\frac{640 × 2.5 × t }{100}\) t = 8 years