Ex 13.2

Chapter 13 Class 11 Statistics
Serial order wise

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### Transcript

Ex 13.2, 2 Find the mean and variance for the first n natural numbers First n natural numbers = 1, 2, 3, 4, β¦β¦ n Mean = (1 + 2 + 3 + 4 + β¦β¦. + n)/n = (n(n + 1)/2)/π = (π§ + π)/π Variance (Ο2) = (ββ(π₯_π β π₯ Μ )^2 )/n As the data is very large hence, "(xi β " π₯ Μ")" 2 calculation is difficult. Hence, we can use the formula : β΄ Variance (Ο)2 = (π(n + 1)(2n + 1))/6πβ (n + 1)2/4 = ((n + 1)(2n + 1))/6β (n + 1)2/4 = ((π + 1))/2 ((2n + 1)/3 " β " (π + 1)/2) = ((π + 1))/2 ((4n + 2 β 3π β 3)/6) = (π + 1)/2 Γ (π β 1)/6 = (π§^π β π)/ππ

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#### Davneet Singh

Davneet Singh has done his B.Tech from Indian Institute of Technology, Kanpur. He has been teaching from the past 13 years. He provides courses for Maths, Science, Social Science, Physics, Chemistry, Computer Science at Teachoo.