Answer: The equation of the Malthusian model is P (t) = Cert . Apply the cell
counts to solve for r and C. P (1) = 1000, so Cer = 1000, i.e. r = ln(1000/C).
Also, P (2) = 3000, so Ce2r = 3000, i.e. r = 1
2 ln(3000/C). Setting these equal
and solving, one obtains C = 1000/3. Substituting C into r = ln(1000/C) gives
that r = ln 3.