Answer
See explanation.
Work Step by Step
Equation 26.17 gives the current in a discharging RC circuit as a function of time. One can measure the initial current $I_o$, the current $I$ at a known time t after the switch is closed, and the capacitance.
From these values, the unknown resistance R may be determined.
$R=\frac{-t}{C\;ln(I/I_o)}$
