Originally Posted by

**bryangoodrich** Reviewing probability theory from Casella and Berger "Statistical Inference," I saw an example that reminded me of this (see page 24). I used the same approach and got the same answer Plato did (i.e., 13 throws). The book wanted to know the probability for the event that a gambler could throw at least 1 six in 4 rolls of a die. We get

On reflection, I wonder if this is correct, though. It could be bad intuition, but I want to say there is a lack of independence between the rolls and we have to discount something (which might raise k to 17, unless we are concluding the given solution was in error). I say this because while this formula works for independent events for a given number to appear in k rolls, each roll has a chance to reveal one of the 6. So I may not, say, roll a six on the first roll, but I an guaranteed to roll *something* on the first roll. I'm probably wrong, but that kept me from thinking my approach was valid. However, when I got the same answer Plato did, I thought I would comment.