Answer:
The population is of 500 after 10.22 hours.
Step-by-step explanation:
The rate of change of the population of a certain organism is proportional to the population at time t, in hours.
This means that the population can be modeled by the following differential equation:
![\frac{dP}{dt} = Pr](https://tex.z-dn.net/?f=%5Cfrac%7BdP%7D%7Bdt%7D%20%3D%20Pr)
In which r is the growth rate.
Solving by separation of variables, then integrating both sides, we have that:
![\frac{dP}{P} = r dt](https://tex.z-dn.net/?f=%5Cfrac%7BdP%7D%7BP%7D%20%3D%20r%20dt)
![\int \frac{dP}{P} = \int r dt](https://tex.z-dn.net/?f=%5Cint%20%5Cfrac%7BdP%7D%7BP%7D%20%3D%20%5Cint%20r%20dt)
![\ln{P} = rt + K](https://tex.z-dn.net/?f=%5Cln%7BP%7D%20%3D%20rt%20%2B%20K)
Applying the exponential to both sides:
![P(t) = Ke^{rt}](https://tex.z-dn.net/?f=P%28t%29%20%3D%20Ke%5E%7Brt%7D)
In which K is the initial population.
At time t = 0 hours, the population is 300.
This means that K = 300. So
![P(t) = 300e^{rt}](https://tex.z-dn.net/?f=P%28t%29%20%3D%20300e%5E%7Brt%7D)
At time t = 24 hours, the population is 1000.
This means that P(24) = 1000. We use this to find the growth rate. So
![P(t) = 300e^{rt}](https://tex.z-dn.net/?f=P%28t%29%20%3D%20300e%5E%7Brt%7D)
![1000 = 300e^{24r}](https://tex.z-dn.net/?f=1000%20%3D%20300e%5E%7B24r%7D)
![e^{24r} = \frac{1000}{300}](https://tex.z-dn.net/?f=e%5E%7B24r%7D%20%3D%20%5Cfrac%7B1000%7D%7B300%7D)
![e^{24r} = \frac{10}{3}](https://tex.z-dn.net/?f=e%5E%7B24r%7D%20%3D%20%5Cfrac%7B10%7D%7B3%7D)
![\ln{e^{24r}} = \ln{\frac{10}{3}}](https://tex.z-dn.net/?f=%5Cln%7Be%5E%7B24r%7D%7D%20%3D%20%5Cln%7B%5Cfrac%7B10%7D%7B3%7D%7D)
![24r = \ln{\frac{10}{3}}](https://tex.z-dn.net/?f=24r%20%3D%20%5Cln%7B%5Cfrac%7B10%7D%7B3%7D%7D)
![r = \frac{\ln{\frac{10}{3}}}{24}](https://tex.z-dn.net/?f=r%20%3D%20%5Cfrac%7B%5Cln%7B%5Cfrac%7B10%7D%7B3%7D%7D%7D%7B24%7D)
![r = 0.05](https://tex.z-dn.net/?f=r%20%3D%200.05)
So
![P(t) = 300e^{0.05t}](https://tex.z-dn.net/?f=P%28t%29%20%3D%20300e%5E%7B0.05t%7D)
At what time t is the population 500?
This is t for which P(t) = 500. So
![P(t) = 300e^{0.05t}](https://tex.z-dn.net/?f=P%28t%29%20%3D%20300e%5E%7B0.05t%7D)
![500 = 300e^{0.05t}](https://tex.z-dn.net/?f=500%20%3D%20300e%5E%7B0.05t%7D)
![e^{0.05t} = \frac{500}{300}](https://tex.z-dn.net/?f=e%5E%7B0.05t%7D%20%3D%20%5Cfrac%7B500%7D%7B300%7D)
![e^{0.05t} = \frac{5}{3}](https://tex.z-dn.net/?f=e%5E%7B0.05t%7D%20%3D%20%5Cfrac%7B5%7D%7B3%7D)
![\ln{e^{0.05t}} = \ln{\frac{5}{3}}](https://tex.z-dn.net/?f=%5Cln%7Be%5E%7B0.05t%7D%7D%20%3D%20%5Cln%7B%5Cfrac%7B5%7D%7B3%7D%7D)
![0.05t = \ln{\frac{5}{3}}](https://tex.z-dn.net/?f=0.05t%20%3D%20%5Cln%7B%5Cfrac%7B5%7D%7B3%7D%7D)
![t = \frac{\ln{\frac{5}{3}}}{0.05}](https://tex.z-dn.net/?f=t%20%3D%20%5Cfrac%7B%5Cln%7B%5Cfrac%7B5%7D%7B3%7D%7D%7D%7B0.05%7D)
![t = 10.22](https://tex.z-dn.net/?f=t%20%3D%2010.22)
The population is of 500 after 10.22 hours.