Confidence Intervals z-distributions Name: _________________________________ Statistics What is the critical value (z*) for the following confidence levels? 80% confidence 96% confidence 99.8% confidence The NAEP (National Assessment of Educational Progress) includes a short test of quantitative skills, covering basic arithmetic and the ability to apply it. Suppose a random sample of 60 young adult men are taken from a large population. (Assume = 60) σ a) Describe the of the sampling distribution of. Justify your answer. b) If the mean of the sample is 265, what is a 90% confidence interval? c) If a 95% confidence interval is 256.82 to 287.18, what is the mean of the sample? d) What does 95% confidence mean? 3) Crop researchers plant 34 plots with a new variety of corn. The average yield in bushels per acre is 123.33. (Assume = 15) σ What is the shape of the sampling distribution of? Explain. Find the 90% confidence interval for the mean yield for this variety of corn. μ Find the 95% confidence interval. Find the 99% confidence interval. How do the margins of error change as the confidence level increases?
Confidence Intervals z-distributions Name: _________________________________ Statistics What is the critical value (z*) for the following confidence levels? 80% confidence 96% confidence 99.8% confidence The NAEP (National Assessment of Educational Progress) includes a short test of quantitative skills, covering basic arithmetic and the ability to apply it. Suppose a random sample of 60 young adult men are taken from a large population. (Assume σ = 60) a) Describe the of the sampling distribution of. Justify your answer. b) If the mean of the sample is 265, what is a 90% confidence interval? c) If a 95% confidence interval is 256.82 to 287.18, what is the mean of the sample? d) What does 95% confidence mean? 3) Crop researchers plant 34 plots with a new variety of corn. The average yield in bushels per acre is 123.33. (Assume σ = 15) What is the shape of the sampling distribution of? Explain. Find the 90% confidence interval for the mean yield μ for this variety of corn. Find the 95% confidence interval. Find the 99% confidence interval. How do the margins of error change as the confidence level increases?
confidence_intervals_z-distributions.docx