Ex 15.2, 9 - Chapter 15 Class 11 Statistics (Term 1)
Last updated at May 29, 2018 by Teachoo
Ex 15.2
Ex15.2, 9 Find the mean, variance and standard deviation using short-cut method Mean(π₯ Μ ) = A + (ββπππ¦π)/(ββππ) Γβ where A = assumed mean = 92.5 π¦_π=(π₯_π β π΄)/β h = class size = 75 β 70 = 5 Variance (π)2 = β2/N2 [πββπππ¦π2 β (ββπππ¦π)^2 ] = 52/602 [N Γ (254) β (6)2] = 25/3600 [60 Γ254 β36] = 25/3600 Γ 15204 = 105.58 β΄ Standard deviation (π) = βVariance = β105.58 = 10.27