00:02
So we're going to use that formula to solve this problem.
00:06
We have an initial amount of salt is 25 kilograms.
00:10
And after 10 hours, we have 15 milligrams.
00:13
And the only reason they're giving us that is so we find k.
00:17
We don't know what that is.
00:18
So over here, we're going to put in the initial amount was 25.
00:23
And the rate, or actually that should say k.
00:26
So the k value we don't know.
00:28
And the time is 10 hours.
00:30
And after 10 hours it was 15 milligrams.
00:35
So we're going to solve that.
00:37
So we have 15 divided by 25, which we could really say three -fifths on, divide both them by five.
00:44
And then we have e to the 10 -k.
00:47
So we're going to have natural log of three -fiths equals 10 -k.
00:56
So we are going to do that on our calculator.
00:58
Let me pull that up.
01:00
There it is.
01:07
There we go.
01:08
Natural log, three divided by five...