The simple interest on a certain sum of money at rate of interest 5% per annum for 2 years is Rs. 500. What is the compound interest in rupees on the same sum for the same period and at the same rate of interest?

512.5

Total Simple Interest for two years = 5× 2= 10%

ATQ, 

S.I = 10% of Principal = Rs.500

Principal = Rs.5000

Now,

Total Compound Interest for two years = 5% + 5% + \(\frac{5% of 5%}{100}\) = 10.25%

Therefore,

C.I. for two years = 10.25% of Principal

                          = 10.25% of Rs.5000

                          = Rs.512.50