Assume that in 2014, in 1871 $20 double eagle sold for $17,000. what was the rate of return on this investment

The rate of return is the amount received on top of the cost of the initial investment divided by the initial investment made.

  Profit = $17,000 - $20
  Profit = $16,980

Dividing the calculated by the initial investment and the number of years.
      Rate of return = (($16980/$20)(100%) / (2014 - 1871)
      Rate of return = (84900%) / 143
                             = 593.71%

ANSWER: 593.71%