multiplication rule, additiona rule and total probability rule

[HJC]

This is probably the area I have spent the most time on and got knowwhere fast. So thought I would post here too see if anybody has any external links or advice on how to answer these questions. I feel like just knowing the formulas for these questions doesnt help at all. If I dont get it by now should I just move on? I don’t want to waste to much more time otherwise I will neglect the last month I have.
Thanks in advance.

 

[Harrogath]

Just count the number of LOS in the entire curriculum. I think they about 500+, the # of questions is 240, so on average, each LOS has less than 1/2 ocurrence. In my opinion, the range of questions that one LOS could be tested goes from 0 to 2 which means that a given LOS can not be tested or even tested in 2 questions, but not more.
Let’s say that Prob Rules are tested twice on the real exam. That is 2/240 realtive certain fail = 0.83% loss in total score. If you lucky there is only 1 question, the loss is the half.
If it is too complicated to master, just go and save other LOS that can be mastered, your certain score goes up.
Using probabilities are good for strategy, so try to cheer up with them.

 

[madesofspades]

The rules in theory never make sense to me. What does make sense is when I calculate the probability in my head. Definitely punting this LOS for the exam, hoping I can guess and check my way into the right answer.