Bayes’ Theorem

Find the probability of A occurring given that B occurs.

Use a tree diagram to work out the probabilities.

Multiply when going deeper into a tree…
Add when combining separate branches….
So probability of getting a Q would be…
P(Q) = (1/3) . (1/2)    +   (2/3) . (1/4)   = 1/6 + 1 / 6 = 1/3

Example from patrickJMT
https://www.youtube.com/watch?v=j2tNxIaGpR4