A pair of dice is being rolled. The probability for rolling a sum greater than 8 is 10/36. Is the probability for it taking two rolls to attain a sum greater than 8 just 26/36 times 26/36? I need to make a table of the number of rolls it takes to obtain a sum greater than 8, and the probability that it will take that many rolls. What equation do I use? Assume n is the number of rolls it takes. EDIT: I think I figured it out as I was walking away from the comp. Is it (26/36)^(n-1) * (10/36)? Assuming it is, how do you find the average number of rolls it takes to get that? It looks to be about 2.4. But how do I calculate that? Is it just 36/10 or 3.6?