Suppose that you are given the task of learning \(100 \%\) of a block of
knowledge. Human nature tells us that we would retain only a percentage \(P\) of
the knowledge \(t\) weeks after we have learned it. The Ebbinghaus learning
model asserts that \(P\) is given by
$$
P(t)=Q+(100 \%-Q) e^{-h t}
$$
where \(Q\) is the percentage that we would never forget and \(h\) is a constant
that depends on the knowledge learned. Suppose that \(Q=40 \%\) and \(k=0.7\)
a) Find the percentage retained after \(0 \mathrm{wk}\); 1 wk; 2 wk; 6 wk; 10
wk.
b) Find \(\lim _{\ell \rightarrow \infty} P(\iota)\)
c) Sketch a graph of \(P\).
d) Find the rate of change of \(P\) with respect to time \(t, P^{\prime}(t)\).
e) Interpret the meaning of the derivative.