ANSWER
Approximately after 15 minutes.
EXPLANATION
The growth rate of the first bacteria is
[tex]y = 2 {t}^{2} + 3t + 500[/tex]
The growth rate of the first bacteria :
[tex]y = 3 {t}^{2} + t + 300[/tex]
To find the time that, there will be an equal number of bacteria, we equate the two equation;
[tex]3 {t}^{2} + t + 300 = 2 {t}^{2} + 3t + 500[/tex]
[tex]3 {t}^{2} - 2 {t}^{2} + t - 3t + 300 - 500 =00[/tex]
[tex] {t}^{2} - 2t - 200= 0[/tex]
We solve for t to get,
[tex]t = 15.177[/tex]
Or
[tex] t = - 13.177[/tex]
We discard the negative value.
This implies that,
[tex]t \approx15[/tex]