Hi, I would like to confirm my answer to the following question in Statistics. Hopefully one of you will be willing to provide some feedback. 1. The problem statement, all variables and given/known data A die is tossed repeatedly, until a result (1-6) equal to one of the preceding results is obtained. For instance, (3,2,4,2) is a series of tosses halted at the fourth toss (as only after that toss has a number recurred). X denotes the number of tosses till 'success' is obtained. The question asks for the probability function of X. 2. Relevant equations 3. The attempt at a solution I wasn't sure how to come up with a general formula for P(X), but I did manage to derive the following, which, hopefully, is correct: P(X = 2) = 1/6 P(X = 3) = (5/6)(2/6) = 5/18 P(X = 4) = (5/6)(4/6)(3/6) = 5/18 P(X = 5) = (5/6)(4/6)(3/6)(4/6) = 5/27 P(X = 6) = (5/6)(4/6)(3/6)(2/6)(5/6) = 25/324 P(X = 7) = 5! / 6^5 = 5/324 Is it correct? How may I come up with a general formula for P(X)? I'd appreciate any comments and your assistance.