00:01
A sample began with 900 bacteria.
00:06
So that is our initial amount.
00:09
And then after 17 minutes, we had 450 bacteria.
00:20
So i'm going to use that.
00:24
And an exponential decay model to find the decay rate.
00:29
So my a sub -zero is 900.
00:32
And then i'm going to end up with 440.
00:35
And the time for that is 17 minutes.
00:40
Divide both sides by 900.
00:46
So you're getting really the half -life here.
00:57
Take the ln of both sides.
01:02
Bring your exponent down in front.
01:06
Ln of e is just one, divide both sides by 17...