Last year, the weekly salary of a worker is approximately a normal distribution with mean $100 and standard deviation $30. An analyst suspects that the weekly salary and the percentage of weekly salaries over $100 have gone up significantly this year. The analyst selects a random sample of 225 workers this year. The sample shows an average weekly salary of $112 with a standard deviation of $36; and 153 salaries in this sample are more than $100. Answer questions (a) and (b) below using a 5% significance level. You must write down the null and alternative hypoth
Last year, the weekly salary of a worker is approximately a
Answer questions (a) and (b) below using a 5% significance level. You must write down the null and alternative hypotheses, the decision rule, the test statistic, and the conclusion.
(a) Test if the average weekly salary this year is significantly more than that of last year.
(b) Test if the percent of weekly salaries over $100 this year is significantly more than that of last year.
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