Find the compound interest on Rs. 6400 for 2 years compounded annually at % per annum.

13 The population of a village is 50000. It increases by 5% every year. Find the population at the end of 2 years. 14 The population of a city increases by 4% of what it had been at the beginning of each year. If the population in 1997 had been 6760000, find the population of the city in (i) 1999 (ii) 1995. 16 Find the compound interest on Rs. 15625 for years at 8% per annum when compounded half-yearly. 17 Find the compound interest on Rs. 160000 for 2 years at 10% per annum when compounded semi-annually.