Hypothesis test for the difference of population means: Z test
Past records suggest that the mean annual income, , of teachers in state of Utah is greater than or equal to the mean annual income, , of teachers in Oregon. In a current study, a random sample of teachers from Utah and an independent random sample of teachers from Oregon have been asked to report their mean annual income.The data obtained are as follows.
Annual income in dollars
Utah
Oregon
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The population standard deviation for mean annual income of teachers in Utah and in Oregon are estimated as and respectively. It is also known that both populations are approximately normally distributed. At the level of significance, is there sufficient evidence to reject the claim that the mean annual income of teachers in state of Utah is greater than or equal to the mean annual income of teachers in Oregon? Perform a one-tailed test.
Carry your intermediate computations to at least three decimal places and round your answers as specified in the table. (If necessary, consult a list of formulas.)