Two annuities - certain of 1 p.a. are each payable half-yearly for a years. The first payment under one is due at the end of 3 months and under the other at the end of 6 months from now. The total present value of the two annuities is 20.255. The amount of an annuity of 1 per quarter in arrear for n years is 47.719. If the same effective rate of interest applies throughout, find n and the rate of interest.
