[SOLVED] Bernoulli, Poisson & Normal Probability The problem statement, all variables and given/known data Every chocolate bar contains 100 squares, with 10% of the individual squares presenting a health hazard to people consuming them. (a) Using the Binomial, Poisson and Normal distributions, write down formulas for the probability that a single chocolate bar has at least 3 but no more than 7 deadly squares. The attempt at a solution For the binomial part, I've just done Pr(x=3) + Pr(x=4) +.... Pr(x=7). Just wondering if that's what you would do? I've done the same for the Poisson, using μ = 10. I'm stuck on Normal distribution though. I'm thinking of using http://img294.imageshack.us/img294/5079/untitledzi8.jpg [Broken] but I don't know σ.