Bayes Theorem

If you can solve a Bayes question by drawing a tree… do you need to know the P (A given B ) and all that formula nonsense? Sorry to put it in harsh terms!

If so, whats a good way to remember them?


I wrote up an article on this with trees and formulae and everything.

The simple answer is that you generally don’t need to use the formula; draw a tree and it’s easy. If you want to remember the formula, it’s actually really easy; just remember the formulae for P(AB):

P(A|B)P(B) = P(AB) = P(B|A)P(A)

P(A|B)P(B) = P(B|A)P(A)

Divide both sides by P(B) and you have Bayes’ Formula. Easy peasy.

Magician could you post the link of the explication? I have so many problems with probability questions

Look under CFA Test Prep, Tutoring Services (above).

yup, LOVE Those posts. THANKS!