If a variable X takes values 0, 1, 2, ….., n with frequencies n C 0 , n C 1 , n C 2 , ……. n C n , then write variance X.

If a variable X takes values 0, 1, 2, ….., n with frequencies ⁿC₀, ⁿC₁, ⁿC₂, …….ⁿC_n, then write variance X.

we know, mean x =

Hence,

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