So I have an event that can occur on a daily basis with probabilty 1%. There is no dependence between days. Now I can calculate the probabality of the event occuring X times in Y days:
COMBIN(Y,X) * (0.01 ^ X) * [0.99 ^ (Y - X)]
where COMBIN() is the number of combinations for X in Y. Now what I'd like to calculate is the probablity of X events in any Y window for the last Z days, e.g what is the probability of 5 events occuring in at least one 30 day window during the last 10 years. Any assistance much appreciated.
Note: Original question edited to add "at least" qualifier per MansT suggestion below.