Madhava invested Rs. 1500 in Company 'B' in 2005 for two years with a condition to get the compound interest at the same rate as 2005. What was the amount of interest earned?

Compound interest = P(1 + r)^t - P
or Compound interest = P[(1 + r)^t - 1]
where P = the principal investment amount (the initial deposit or loan amount)
r = the annual interest rate
t = the number of years the money is invested or borrowed for.
Required amount of interest earned by Madhava in 2007 = 15000[(1+ 15/100)² - 1]
= 15000[(115/100)² - 1]
= 15000[(23/20)² - 1]
= 15000[(23 x 23 /20 x 20) - 1]
= 15000[ (529/400) - 1]
= 15000[(529 - 400)/400]
= 15000 x 129/400
= 19350/4
= Rs. 4837.50