Business R - ISEG – ISM BUSINESS RESEARCH METHODS Final...

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Unformatted text preview: ISEG – ISM BUSINESS RESEARCH METHODS Final Assignment EXERCISE 1 : Data : μ = 37 σ = 4 n = 25 σ x = n σ = 25 4 = 0.8 So: n σ μ) x ( z   = 0.8 37) (38.2  = 1.5 Referring to the Z table Z (1.5) = 0.4332 So: 0.5 - 0.4332 = 0.0668 corresponding to 6.68% Conclusion : There is 6.68% that the average age of group is greater than 38.2 years old. As 6.68% is very low, we can’t assume that the engineers in this group are g enerally much older than the average. EXERCISE 2 : Data : n = 50 x = 196.02 (data from excel) s = 617.28(data from excel) 90% σ x = n s = 50 617.28 = 87.3097 So : n s z x   196.02  1.65 (87.3097) 196.02 + 144.0610 = $ 340.10 196.02 - 144.0610 = $ 51.96 Conclusion : The 90% confidence interval of the population mean for the incomes of western Pennsylvania credit union is between $ 340.10 and $ 51.96. EXERCISE 3 : Data : n = 8 (<30) x = 58.875 (data from excel) s = 5.083 (data from excel) d.f = n-1 = 7 σ x = n s = 8 5.083 = 1.796 So : n s t x   58.875  1.8946 (1.796) 58.875 + 3.4027 = 62.28 ≃ 62 salaries 58.875 - 3.4027 = 55.47 ≃ 55 salaries Conclusion : The 90% confidence interval of the mean for the salaries of substitute teachers in this region is between 62 and 55 salaries....
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This note was uploaded on 02/14/2010 for the course BR Business R taught by Professor Bob during the Spring '10 term at École Normale Supérieure.

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Business R - ISEG – ISM BUSINESS RESEARCH METHODS Final...

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