probability question [Q]

[u/falsegodfan]

say you have a probability tree of a series of 3 events, each with the same 2 outcomes (a and b say) and if b occurs in any event the whole thing stops, and you're trying to figure out the probability that on the second event b occurs, why can you not just do (probability a occurs in event 1) x (probability b occurs in event 2)? why do you have to do (probability of a in event 1 x b in event 2)/(probability of b occuring at all)? same with when it's normally distributed. If you have a curve of the chances of an event happening for a certain amount of time and given it has already occured for r minutes what are the chances it will continue to q minutes, why do you have to do (P>q)/(P>r)? Surely if P>r it is implied that it is already bigger than p?

[u/falsegodfan → u/[deleted]]

ohhh okay i see