the compound interest of a sum of money for 1 year and 2 years are rs

1.	the compound interest of a sum of money for 1 year and 2 years are rs 450 and rs 945 respectively. find the rate of interest compounded yearly and he sum
Answer» ANSWER $SI= 100PRT$ $Hence,400= 100PR2$ $⟹PR=20000⟹P= R20000$ $Also,CI=P[(1+ 100R ) 2 −1]420= R20000$ $[(1+ 100R ) 2 −1]$ SOLVING this we GET R=10% ALTERNATE:− $CI for 2 years is=420 Rs.SI for 2 years is=400 Rs.Difference of CI and SI is 420−400=20 Rs.$ $If 2 years SI is 400 Rs.,then 1 year SI is = 2400 =200$ $20 is the what percent of 200.=20×( 200100 )=10%$ $If 510% is 200 Rs. then 100% of that principal.=200× 10100 =2000$ $So the principal is 2000 Rs.Hence,R= PTSI×100 = 2000×2400×100 =10\%$