Answer:
a) In the year 1998 with 3 days, 2 hours, 44 minutes and 18.1006141 seconds
b) In the year 1998 with 19 days, 18 hours, 5 minutes and 35.10875472 seconds
Step-by-step explanation:
a) To know the time when the population will be 305 million people, we need to isolate the variable t in the equation, 
So we isolate t with the property of logarithms that allow us go down the exponent, applying in both sides of the equation
For this subsection the value of P is equal to 305 million people
![Ln(305)=Ln[(288)(1.009)]^{t-1997}](https://tex.z-dn.net/?f=Ln%28305%29%3DLn%5B%28288%29%281.009%29%5D%5E%7Bt-1997%7D)
![Ln(305)=(t-1997)*Ln[(288)(1.009)]](https://tex.z-dn.net/?f=Ln%28305%29%3D%28t-1997%29%2ALn%5B%28288%29%281.009%29%5D)
Now, we can isolate the value of t
![\frac{Ln(305)}{Ln[(288)(1.009)]} =t-1997](https://tex.z-dn.net/?f=%5Cfrac%7BLn%28305%29%7D%7BLn%5B%28288%29%281.009%29%5D%7D%20%3Dt-1997)
![\frac{Ln(305)}{Ln[(288)(1.009)]}-1997 =t](https://tex.z-dn.net/?f=%5Cfrac%7BLn%28305%29%7D%7BLn%5B%28288%29%281.009%29%5D%7D-1997%20%3Dt)

So to know the exact date we multiply the number after the point, that is 0.008531776402 for the number of days that have 1 year, equal to 365 days
0.008531776402*365= 3.114098387 days
then the number after the point, that is 0.114098387 will be multiply for the number of hours that have 1 day
0.114098387*24= 2.738361282 hours
then the number after the point, that is 0.738361282 will be multiply for the number of minutes that have 1 hour
0.738361282*60= 44.3016769 minutes
Finally, the number after the point, that is 0.3016769 will be multiply for the number of seconds that have 1 minute
0.3016769*60= 18.1006141 seconds
And we obtain that the time, when the population of the country is 305 million people, is in the year 1998 with 3 days, 2 hours, 44 minutes and 25.152 seconds
b) For calculate the time when the population is 395 million people, we do the same process we did in the subsection a)
![Ln(395)=Ln[(288)(1.009)]^{t-1997}](https://tex.z-dn.net/?f=Ln%28395%29%3DLn%5B%28288%29%281.009%29%5D%5E%7Bt-1997%7D)
![Ln(395)=(t-1997)*Ln[(288)(1.009)]](https://tex.z-dn.net/?f=Ln%28395%29%3D%28t-1997%29%2ALn%5B%28288%29%281.009%29%5D)
Now, we can isolate the value of t
![\frac{Ln(395)}{Ln[(288)(1.009)]} =t-1997](https://tex.z-dn.net/?f=%5Cfrac%7BLn%28395%29%7D%7BLn%5B%28288%29%281.009%29%5D%7D%20%3Dt-1997)
![\frac{Ln(395)}{Ln[(288)(1.009)]}-1997 =t](https://tex.z-dn.net/?f=%5Cfrac%7BLn%28395%29%7D%7BLn%5B%28288%29%281.009%29%5D%7D-1997%20%3Dt)

0.05412021527*365= 19.75387857 days
0.75387857 *24= 18.09308577 hours
0.09308577*60= 5.585145912 minutes
0.585145912*60= 35.10875472 seconds
And we obtain that the time, when the population of the country is 395 million people, is in the year 1998 with 19 days, 18 hours, 5 minutes and 35.10875472 seconds