1. The problem statement, all variables and given/known data Probability of a car starting up is 0.9 Probability of a car NOT starting up is 0.1 Cars are tested until 2 functional cars are found. Find Bernoulli probability function associated and PROVE that it is a pdf (probability density function). 2. Relevant equations ? 3. The attempt at a solution To prove that it is a pdf, I think that I need to sum up all of the probabilities associated with the x values and show that it equals 1. [tex]\Sigma[/tex]x=2 to infinity p^2*(1-p)^(x-2) How do I show that this equals 1? Is it even correct? Keep in mind that the minimum value for the # of cars tested is 2 because we're looking for 2 functional cars, and once we've got 2, we stop the trials.