Solving Half-Life Problems 

In this video we go over the equation for solving half-life problems. Then we do some examples where we solve for the amount of the substance you have left after a given amount of time. Finally we do some examples where we solve for time given everything else. You definitely need logs to solve that type so we also go over the properties of logs that you need to know. Here's an index of what we do in case you want to jump around:
0:25 log properties you need to solve half-life problems
1:35 the half-life equation and what everything means
2:44 three examples of solving for how much is left after a given time
5:14 solving for time until a certain amount is left (needs logs!)
See how to do these sorts of things on your TI-Nspire: • Half-Life Problems on ...