A learning curve is a graph of a function P(t) that measures the performance of someone learning a skill as a function of the training time t. At first, the rate of learning is rapid. Then, as performance increases and approaches a maximal value M, the rate of learning decreases. It has been found that the function P(t) = M - Ce-kt, where k and C are positive constants and C
(a) Express the learning time t as a function of the performance level P.