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A critic of Canada Post claims that its financial returns are typically $200 million less than forecast. In five of the years of the 1990s, the mean difference (in millions of dollars) between Canada Post s forecast and actual financial positions was 218.8, with a standard deviation of 118.76 (based on Canada Post data reported by Maclean Hunter, 1996). Use a significance level of 0.05 to test the claim that the mean difference between forecasted returns and actual returns was 200.
Use the traditional approach summarized. Draw a graph showing the test statistic and critical values. In each case, assume that the population has a distribution that is approximately normal and that the sample is randomly selected. |
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