00:02
Okay, the initial population is population at time zero.
00:09
So just let t equal zero.
00:17
So that gives me 1 ,300 divided by 1 plus 4 or 1 ,300 divided by 5.
00:28
My initial population was 260 fish.
00:36
What is the doubling time? so the doubling time is the amount of time it takes for my initial population to double.
00:51
So i want to set my function equal to 260 times 2.
01:06
Now, 260 times 2 is just 520.
01:11
So i'm going to have 1 plus 4e to the negative 0 .65t.
01:18
Equal to 1 ,300 divided by 520.
01:23
1 ,300 divided by 520 is 2 .5.
01:36
Subtract 1, and then divide both sides by 4.
01:48
So i'm going to have e to the negative.
01:51
0 .65t equals 1 .5 divided by 4, which is 0 .375.
01:59
Take the natural log of both sides.
02:05
Drop your negative exponent down.
02:08
Ln of e is just equal to 1.
02:12
Divide both sides by negative .6 .5.
02:16
And we'll have our doubling time.
02:18
Ln of 0 .375 divided by negative .6.
02:24
It's going to give me a doubling time of 1 .509.
02:30
So about 1 .5 years...