I want to calculate the overall probability of an event occurring over n trials such that the probability is increased after a certain $n_1^{th}$ trial.
So to elaborate, let's say the total number of trials are 90(using some numbers from my original problem) The probability of the event occurring before 76th trial is 0.006 and each trial is independent. And for trials 76-89 the probability is 0.324 and again within these trials, the trials are independent. If the event doesn't occur before the 90th trial, the event will definitely occur on the 90th trial, and the probability becomes 1.
So how do I calculate the overall probability of that event over the 90 trials.
I think that over 90 trials the probability should be 1 because, the event is definitely going to occur in 90 trials. So it might better to calculate it for 89 trials.