Statistical Sciences 2035 Lecture Notes - Lecture 3: Box Plot, Kurtosis, Cumulative Frequency Analysis
6 Oct 2017
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In calculating the mean of a population or sample, we sum each measurement and divide by the number of measurements: that is, each measurement is given the same importance or weight. But sometimes it makes sense to give different measurements unequal weights: when we do this, we will calculate what is referred to as a weighted mean xw i. Weighted mean = where wi = weight applied to the ith measurement xi = value of the ith measurement i w i. The following are the final marks in 5 different introductory economics classes: Solution (xbar) = 125/640 x (74. 2) + 176/640 x (68. 7) w = 45773. 1/640 = 71. 52% (ii) mean and variance of grouped data. Sample variance for grouped data xmf i i. 2 s2 = where fi = frequency for class i. Mi = midpoint of class i n = sample size = if. Calculate the mean and standard deviation of the marketing manager salaries.
