Answer:
The estimated number of bacteria after 20 hours is 40.
Step-by-step explanation:
This is a case where a geometrical progression is reported, which is a particular case of exponential growth and is defined by the following formula:
[tex]n(t) = n_{o}\cdot \left(1+\frac{r}{100} \right)^{t}[/tex] (1)
Where:
[tex]n_{o}[/tex] - Initial number of bacteria, dimensionless.
[tex]r[/tex] - Increase growth of the experiment, expressed in percentage.
[tex]t[/tex] - Time, measured in hours.
[tex]n(t)[/tex] - Current number of bacteria, dimensionless.
If we know that [tex]n_{o} = 30[/tex], [tex]r = 1.4[/tex] and [tex]t = 20\,h[/tex], then the number of bacteria after 20 hours is:
[tex]n(t) = 30\cdot \left(1+\frac{1.4}{100} \right)^{20}[/tex]
[tex]n(t) \approx 39.616[/tex]
[tex]n(t) = 40[/tex]
The estimated number of bacteria after 20 hours is 40.