55. (Requires a spreadsheet) Jack Whittaker of West Virginia, on Christmas Day in 2002, won the jackpot worth $314.9 million in a lottery with “annuity value.” (His subsequent life has been far from a fairy tale, as a Google search will reveal.) Instead of receiving $314.9 million in 30 equal annual payments, including one immediately, he chose a lump sum, which came to $170 million. What was the corresponding interest rate of the annuity?