Quicken Loans, the Detroit based mortgage lender, with the backing of Warren Buffet's Berkshire Hathaway has offered $1 billion to anyone who fills out a perfect 2014 NCAA men's basketball tournament bracket (guesses the winners for each of 64 games). The $1 billion is paid in 40 annual payments or you can take a lump sum of $500 million. What annual interest rate was used to determine the present value of the $1 billion prize?