Combined Cumulative Probabilities of Success If you undertake an iterative action 10 times and each time the probability of that action failing is 4% each time, how do you calculate the probability that the outcome of all 10 actions will be successful (meaning, each of the 10 action must succeed)? The result I am getting is 66.5% Now, how do you calculate the probability that if this iterative 10-step action were taken twice at the same time by different actors at least ONE of the actors would succeed?

The probability of success of single actor is approximately $0.665$. The probability they both fail the task is approximately $(1-0.665)^2$. The probability at least one will succeed is...