Exponential and Logarithmic Functions

Question

The rate at which a battery charges is slower the closer the battery is to its maximum charge C₀. The time (in hours) required to charge a fully discharged battery to a charge C is given by

t = -k ln (1-C/C0)

where k is a positive constant that depends on the battery. For a certain battery, k = 0.2. If this battery is fully discharged, how long will it take to charge to 60% of its maximum charge C₀? (Round your answer to three decimal places.) 

Answer 1

then, t = (-.2)ln(1 - .6C_o/C_o) = (-.2)ln(1-.6) = .183 hours