A population of amoebas in a petri dish will triple in size every 20 minutes. at the start of experiment the population is 800.

If we are to derive the equation that models the growth of the amoeba, we make use of the general form:

p = po k^t

where po is the initial population

k is the multiplicative rate of change

From the problem

3po = po k^ (20)

k = 1.06

The equation is

p = 800 (1.06) ^t