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A researcher collects crash data at 12 intersections in NYC and found an average crash rate of 4

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A researcher collects crash data at 12 intersections in NYC and found an average crash rate of 4.76 crashes/year with a standard deviation of 0.47 crashes/year. A. What is the 80% confidence interval on the mean? B. What is the 95% confidence interval on the mean? C. Is the crash data at these 12 intersections different than the city average of 4.56 crashes/year at a 20% level of significance? Define your null and alternative hypothesis. Show your work. D. Is the crash data at these 12 intersections different than the city average of 4.56 crashes/year at a 5% level of significance? Define your null and alternative hypothesis. Show your work.