Ionutzakis

i always use the tree too, and then just have to apply total probability and bayes formula.
Actually with the tree, if you are asking the proba of smthg that is in the root of your tree, (in this case energy or not), then you know you'll have to use bayes formula after calculating the probability of the leave of your tree using the total proba.

If you're asking the proba of smthg on the leaves regardless of the roof, then total probality only

And if smthg on the leaves given the roof, conditional proba