City planners are concerned if the mean lifetime of the most commonly planted trees in urban settings is more than 30 years. A sample of 42 recently fallen trees yielded a mean age of 30.7 years with...

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Extracted text: City planners are concerned if the mean lifetime of the most commonly planted trees in urban settings is more than 30 years. A sample of 42 recently fallen trees yielded a mean age of 30.7 years with standard deviation of 3.2 years. esis test at


Extracted text: (b) If the mean lifetime is actually 31 years, what is the probability we will reject the null hypothesis at a 0.05 significance level? What sample size would be necessary to ensure that Type II error (c) is 0.1 when the mean lifetime is 31 years?