Since the yeast divides every two hours, its population (and hence yeast mass) doubles every two hours. Because the doubling time is a constant it is exponential growth.
The mass of yeast grows exponentially with time as : m(t)=moexp(λt);⇒λ=ln(2)τ,
where λ is the growth factor and τ is the doubling time.
We are given the doubling time (τ) and the initial mass m0 and are asked to estimate t for m(t) to reach the value of the mass of a typical human. Let us assume 75 kg as the mass of a typical human, so m(t)=75 kg.