Conditional Probability
You're right in the middle of the conditional probability part of the course now. The 5.4 WebAssignments were due a few days ago, and the 5.5 assignments are due on Monday. The 5.5 videos throw tree diagrams into the mix. This gives a very nice way of visualizing lots of simply conditional probability situations. But you can't toss the techniques learned in 5.4 out the window, because lots of situations involve way too many possibilities to put everything in a tree. (The tree would be HUGE!) So you have to develop the experience to sense when a tree is useful, and when the outcomes are so numerous that a tree simply isn't feasible. In those cases you have to fall back on your repertoire of counting techniques and use an approach of the type you learned in 5.4
