tire manufacturer claims that its tires have a mean life of at least 50,000 km. A random sample of 25 of these tires is tested and the mean life is 33,000 km. Suppose the population standard deviation is 2,500 km. and the lives of tires is approximately normal. To test the manufacturer’s claim at the 5% level of significance, the analyst should A. perform a right-tailed test using the t-statistic. B. perform a left-tailed test using the t-statistic. C. perform a right-tailed test using the z- stati

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