Question

find the compound interest on rupees 160000 for 1 year at the rate of 20% per annum if the interest is compounded quarterly

Answer 1

formula of finding compound interest is principal *[1 +  rate of interest/ 100]time
so here time is only for one year but compound interest is taken  to be at every 4 months so 4+4+4 = 12 months or a year so in a year 3 time is compound interest is there so 
160000 [1 + 20 / 100 ]3
160000[1+ 0.5]3
160000[1.5]3
160000[3.375]
540000 
now  compound interest is  540000 - 160000 = 380000

Answer 2

hope it will help you :)