A survey of 570 working adults in the United States asked each participant how many hours they worked last week. The survey showed an average of 41.525 hours worked per week, with a standard deviation of 14.828 hours. (Note that this is the average for people that work in the United States, including part-time employees. Among full time employees, the average work week is closer to 47 hours. Link if you’re interested: http://www.gallup.com/poll/175286/hour-workweek-actually-longer-seven-hours.aspx) Is there enough evidence to show that Americans work more than 40 hours per week on average at the 0.01 significance level? Should we perform a Z test or a t test, and why? Select one: a. A z test, because we don't know the population standard deviation b. A t test, because we know the population standard deviation. c. A z test, because we know the population standard deviation. d. A t test, because we don't know the population standard deviation.
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