00:01
We're told that in 1941 there are 20 in a population.
00:05
In 2007 there are 520.
00:10
We're going to assume that the time equals zero in 1941 since that's a starting year for us.
00:18
In the exponential growth equation, a is the starting amount.
00:26
So since we're going to let t equal zero in 1941, the starting amount is 20.
00:33
So a is 20.
00:35
For the value of r, we're going to work off the fact that there are 520 in the year 2007.
00:44
So let's let n equal 520, a equal 20, r is what we're trying to find.
00:55
And for the time 2007 is 66 years after 1941, so t is 66.
01:04
I will divide both sides by 20 to get 26 equals e to the 66 r.
01:14
At this point i'm going to take the natural log of both sides.
01:18
And the reason i want to do that is that the natural log of e to a power is the power.
01:25
So i have 66 r equals natural log 26.
01:29
R is natural log 26 divided by 66...