What sum of money should be invested for 5 years at 18%p.a. to earn intrest as rupees3600 at 10%p.a. for 4 years?? Share with your friends Share 1 Sandeep Saurav answered this Dear Student, SI in the case of principal=3600, rate of interest=10% per annum and time=4 years.SI=PRT100=3600×10×4100=1440Now, to calculate Principal for the same SI at rate of interest=18%per annum and time 5 years.⇒SI=PRT100⇒1440=P×18×5100⇒P=1440×10090=1600So, ₹ 1600 should be invested. Regards -1 View Full Answer