1. The problem statement, all variables and given/known data I am a freshman in physics, just done a lab about radioactive decay. I've measured the # of beta particles per second 400 times and got the frequency of each number K using Excel. I'm supposed to take the data and fit it to a puason distribution in MATlab. The data points themselves seem to be on a nice curve. The problem I'm having is that the equation for the probabilty doesn't seem to curve at all. 2. Relevant equations Puason distribution in radioactive decay: the chance that K beta particles will be detected in 1 second is P(k) = e^-λ * λ^K/K! 3. The attempt at a solution I've made an excel chart which shows λ^K/K! for many different K values, and then tweaked the lambda value. For all the values of λ I've tried, λ^K/K! always increases for increasing values of K, meaning the graph never curves back down. What am I doing wrong?