In the section's notes, example 1, the percent charge in a capacitor is recorded at different times. It makes sense to treat the times chosen as the independent variable and the charge as the dependent variable. Then the charge decays exponentially. Instead, we are asked to have the time depend logarithmically on the capacitor's remaining charge. Similarly in the exercises, questions 3, 5, 7, and 9 look like exponential functions if we use what I think is the common sense choice for dependent and independent variables.