P = $20, the principal in the year 1871.
A = $17,000, the value in the year 2014
t = 2014 - 1871 = 143 years, the duration.
Let r = the yearly return on the investment.
If we assume that the compounding is performed yearly, then
P(1 + r)¹⁴³ = A
That is,
20(1 + r)¹⁴³ = 17000
(1 + r)¹⁴³ = 850
[tex]1+r=850^{1/143}= 1.0483[/tex]
r = 0.0483 = 4.83%
Answer: 4.83%
