# Binomial Distribution with non integer succes

1. Sep 25, 2012

### chargeddyslex

I am doing a problem where I am to determine the probability that the number of students wanting a new book is within two standard deviations of the mean. μ +- 2δ comes out with a non integer number, in which I have to use to find probability. The equation to find probability uses the factorial of this number. Do I round this number to determine the factorial?

2. Sep 25, 2012

### mXSCNT

well if $\mu - 2 \delta$ is 12.3 and $\mu + 2 \delta$ is 17.8 then the number of students wanting the book is within two standard deviations of the mean when the number of students wanting the book is 13, 14, 15, 16, or 17. You can extrapolate.