Recently, a suburban Chicago couple won Power ball, a multi state lottery game. The game had rolled over for several weeks, so a huge jackpot was at stake. Ticket buyers had the choice between a single lump sum of $104 million or a total of $198 million paid out over 25 years (or $7.92 million per year and the payment is made immediately) should they win the game. The winning couple opted for the lump sum. At what interest rate will these two payment options be equivalent?