I am having trouble applying this concept to simple things. Like a die where we let s be the number of spots shown by a die thrown at random. How could I compute the expectation value of s? And how would I compute the mean square deviation. Would the expectation value just be <s>=1/N summation from i=1 to N of si? Here the only possible states are s1,s2,s3,s4,s5, and s6. Help anyone? And how would I calculate the mean square deviation from the equation delta s=<<s-<s>>^2>=<c^2>-<c>^2?