So I'm having trouble solving this exercise: The question is the following, John probability of getting to work late each day is 0.25 . And I'm asked to say how many days there has to be for the probability of John reaching work late once or more is equal to 0.95. I tried doing Binomial Distribution, by doing P(X>=1)=1-[P(X=0)+P(X=1)] and then doing the following equation : 1-[P(X=0)+P(X=1)] =0.95 and then using the Binomial Distribution formula to find the number of days need for the probability to be equal to 0.95. But with no luck, and here I am stuck in this exercise.