size of the yearly retirement annuity

Assume that a 10-year savings annuity of Rs.2,000 per year is beginning at year zero. The retirement annuity is to begin 15 years from now (the first payment is to be received in year 15) and must provide a 20-year annuity. If this plan is arranged through a saving bank that pays interest at the rate of (GDP rate) per year on the deposited funds, what is the size of the yearly retirement annuity that will result? (Note: use GDP rate as an interest rate) First 1 to 10 use GDP rate of 2008 11 to 20 use GDP rate of 2012 21 to 30 use GDP rate of 2016