![Slide17.JPG](https://d1avenlh0i1xmr.cloudfront.net/1b2ea5be-6fc2-418a-a828-30bc6c5edee6/slide17.jpg)
![Slide18.JPG](https://d1avenlh0i1xmr.cloudfront.net/b6421bcc-92e4-4b97-a23d-13f1913a8df2/slide18.jpg)
Last updated at May 7, 2024 by Teachoo
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