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2-3B-Weighted Mean

2-3B-Weighted Mean. Mean of data with varying weights. x = Σ ( x∙w )/ Σ w Multiply each entry by its weight(decimal) A weight of 60% is multiplied by .60 ADD up these values DIVIDE by the sum of the weights (1). Example: find the weighted mean.

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2-3B-Weighted Mean

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  1. 2-3B-Weighted Mean • Mean of data with varying weights. • x = Σ(x∙w)/Σw • Multiply each entry by its weight(decimal) A weight of 60% is multiplied by .60 • ADD up these values • DIVIDE by the sum of the weights (1)

  2. Example: find the weighted mean • Your grade in a class is determined by the following values: Test mean- 50%, midterm – 15%, final exam-20%, labs-10%, homework-5%

  3. Example: find the weighted mean • Your grade in a class is determined by the following values: Test mean- 50%, midterm – 15%, final exam-20%, labs-10%, homework-5%

  4. Example: find the weighted mean • Your grade in a class is determined by the following values: Test mean- 50%, midterm – 15%, final exam-20%, labs-10%, homework-5%

  5. Example: find the weighted mean • Your grade in a class is determined by the following values: Test mean- 50%, midterm – 15%, final exam-20%, labs-10%, homework-5%

  6. Example: find the weighted mean • Your grade in a class is determined by the following values: Test mean- 50%, midterm – 15%, final exam-20%, labs-10%, homework-5%

  7. Frequency Distribution Mean • 1) Find midpoint of each class x = (lower limit + upper limit)/2 • 2) multiply each midpoint & frequency and ADD them all up (sum) Σ(x∙f) • 3) Find SUM of frequencies, n = (Σf) • 4) Find the MEAN of the frequency distrib. x=Σ(x∙f)/n

  8. Example: Find mean number of minutes spent online.

  9. Example: Find mean number of minutes spent online.

  10. Example: Find mean number of minutes spent online.

  11. Example: Find mean number of minutes spent online.

  12. Example: Find mean number of minutes spent online.

  13. Example: Find mean number of minutes spent online. X = Σ(x·f)/n = 2089/50 = 41.8 minutes

  14. Shape of Distributions • 1. Symmetric: left & right same: Mean, median, mode SAME & in middle • 2. Uniform or Rectangular: equal frequencies Also Symmetric: mean median & mode same • 3. Skewed: one side elongates more than other Skewed left: negatively: tail on left mean, median, mode Skewed right: positively: tail on right mode, median, mean

  15. Distribution Examples: Symmetric Uniform (rectangular) Skewed - left Skewed-right

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