According to Fick’s law* f(t) = C(1 − e^−kt), where f(t) is the concentration of solute inside a cell at time t, C is the (constant) concentration of solute surrounding the cell, and k is a positive constant. Suppose that for a particular cell, the concentration on the inside of the cell after 2 hours is 0.8% of the concentration outside the cell.

a. What is k?

b. What is the percentage rate of change of f(t) at time t?