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For a sample size of 10 observations x 1 ,   x 2 ,     . . . x 10 , if ∑ i = 1 10 x i - 5 2 = 350 and ∑ i = 1 10 x i - 2 = 60 , then the variance of x i is

Correct answer

26

Step-by-step solution

∑ i = 1 10 x i - 2 = 60 ⇒ ∑ x i = 80 ∑ i = 1 10 x i 2 - 10 x i + 25 = 350 ⇒ ∑ i = 1 10 x i 2 = 350 + 800 - 250 = 900 Variance is 900 10 - 8 2 = 90 - 64 = 26

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