The equation for the situation is an exponential equation of the form;
- P = 200·

Please find attached the graph of the exponential equation for the population growth, created with MS Excel
What is an exponential equation?; An exponential equation is one in which the argument is an index of a number or quantity.
The initial number of bacteria cells, P₀ = 200
The equation for population growth rate can be presented as follows;
P =

Where; P is the population of the bacteria
P₀ = The initial population of the bacteria
r = The population growth rate
x = The duration of population growth
Where r = 3.5%, P₀ = 20
3.5% = 0.035
Therefore, we get;
P =

Please find attached the graph of the above equation created with MS Excel