Mathematics

Problem

Which of the following is the correct expression for the population variance

\sigma^{2}

of a frequency distribution with class marks

x_i

and corresponding frequencies

f_i

(total frequency

N

)? a)

\displaystyle \sigma^{2}=\dfrac{\sum f_i (x_i-\bar{x})^{2}}{N-1}

\displaystyle \sigma^{2}=\dfrac{\sum (x_i-\bar{x})^{2}}{N}

\displaystyle \sigma^{2}=\dfrac{\sum f_i (x_i-\bar{x})^{2}}{N}

\displaystyle \sigma^{2}=\dfrac{\sum f_i |x_i-\bar{x}|}{N}