# Gaussian distribution

1. Sep 21, 2010

### agentnerdo

The conc.of molecules in two ultra-high-vacuum chambers of volumes V1=V2=0.1m^3 is 10^6 molecules/m3

You count the # of molecules N1 and N2, in each chamber at some moment of time.

a.find the expectation value and the SD of N1 and N2 . calc $$\sigma$$$$_{N1}$$, sketch the prob distribution of N1.

I used SD= sqt(pq) x sqt(N)

=sqt(0.5x0.5) x sqt (2,000,000)
=707.1

I assume for Expectation value i use

W= $$\underline{N!}$$(v/V) (1-v/V)$$^{N-n}$$
n!(N-n)!

I am just sure if N will be 2million, or even what my n will be...

any help be appriciated!