 Okay, so let's try another one of these half-life problems. This one says the half-life of Strontium-90 is 28.1 years. How long will it take a 10 gram sample, a 10.0 gram sample of Strontium-90 to decompose to 0.10 grams, okay? So I've already written it up like how we did the last one. So remember we're using the first order integrated rate law, okay? So if you recall, the way we do these for half-lives is going to be the ln of m0 divided by mT equals kT, like that. But in order to do this problem here, we're going to have to figure out what k is, okay? So k, so what are we solving for? We're going to solve for a T. So k, remember for the first order is going to be ln of 2 divided by the half-life. So we've got the half-life at 28.1 years. So let's figure out what that is. 0.0247 per year. That's the rate constant, okay? So m0, yes, we have that. 10.0 grams divided by mT. We have that. k divided by T. So we want to solve for T. So let's just finish changing this around to solve for T. So T is going to equal that divided by k, 0.0247. Is everybody okay with me doing that? Sorry, I did it on the fly because we don't have much time. Is that all right? Yes. Okay. Okay, so when I do that, I get 0.114 years, okay? Because this is per year. We're going to bring it up to the top, okay? Because it's 1 divided by 1 year, okay? So that's how many years? 0.114 years, okay? We could take this into a different amount of time, like days. Should we do that? Let's do that, okay? I don't know. Does it tell us? It doesn't tell us what time unit it's in. Let's just do it today because it seems more reasonable. So there is 365 days in one year. So it would take 41.5. So that means more to me than 0.114 years. I don't know about you guys. Yeah. It's more unit specific for me. Any questions on this one? No. Okay, I wanted to try.