Answer:
The population size after seven days will be 171.
Explanation:
The population of protozoa can be modeled by the following equation.

In which Q(t) is the population after t days, Q(0) is the initial population and r is the growth rate.
In this problem, we have that:

So

Find the population size after seven days.
This is Q(7).

The population size after seven days will be 171.