The Pacific halibut fishery has been modeled by the differen-
tial equation
$$\frac{d y}{d t}=k y\left(1-\frac{y}{K}\right)$$
where $y(t)$ is the biomass (the total mass of the members of
the population) in kilograms at time $t($ measured in years), the
carrying capacity is estimated to be $K=8 \times 10^{7} \mathrm{kg},$ and
$k=0.71$ per year.
(a) If $y(0)=2 \times 10^{7} \mathrm{kg},$ find the biomass a year later.
(b) How long will it take for the biomass to reach $4 \times 10^{7} \mathrm{kg}$ ?