a sum of money at certain rate of
interest of amount to 8320 in 2years and 9685 in 3 and half years.find the sum ?
assuming compound interest,
s(1+r)^2 = 8320
s(1+r)^3.5 = 9685
dividing, you get
(1+r)^1.5 = 9685/8320 = 1.1640625
1.5 log (1+r) = log 1.1640625
log(1+r) = 0.151916/1.5 = 0.101277361
1+r = 1.10658
Now use that to find s