12 Vacation Days During a recent year, working Americans took on average 18.6 vacation days. This survey was based on a random sample of 16 workers. The standard deviation of the sample was 2.3 days. Find the 99% confidence interval for the mean number of vacation days workers took per year. Assume the population is normally distributed. Use The t Distribution Table. Round intermediate answers to at least three decimal places. Round your final answers to the nearest whole number. Continue Q<

Parents of teenage boys often complain that auto insurance costs more, on average, for teenage boys than for teenage girls. A group of concerned parents examines a random sample of insurance bills. The mean annual cost for 36 teenage boys was $672. For 23 teenage girls, it was $559. From past years, it is known that the population standard deviation for each group is $180. Determine whether or not you believe that the mean cost for auto insurance for teenage boys is greater than that for teenage girls. Conduct a hypothesis test at the 5% level. State the distribution to use for the test. (Round your answers to two decimal places.) What is the test statistic? (If using the z distribution round your answer to two decimal places, and if using the t distribution round your answer to three decimal places.) What is the p-value? (Round your answer to four decimal places.) i. ii. ii.

Salaries of 25 college graduates who took a statistics course in college have a​ mean of $79,350 and a standard​ deviation of $1,280​. Construct a 98​% confidence interval for estimating the population standard deviation. Enter the upper bound of the confidence interval. (Round your answer to nearest whole dollar.)

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What is one property of a stationary time series?   Question 23 options:   The datapoints demonstrate a clear seasonal pattern   The mean remains constant over time   It is plotted as a straight horizontal line   It demonstrates an upward trend

In a survey, 10 people were randomly chosen and asked how much they spent on their auto insurance per year. The results were roughly bell-shaped with a mean of $920 and standard deviation of $107. Find a 99% confidence interval for the true population mean amount of money that typical drivers would spend on their auto insurances. Always write the final answer as a complete sentence. Give your answers rounded to two decimal places. ANSWER: It can be stated with 99% confidence that the true population mean amount of money that people spend on their auto insurance lies in the interval dollars per year Question Help: M Message instructor

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A random sample of 64 shoppers showed that they spend an average of $27.31 per visit at the Sunday Mornings Bookstore. The standard deviation of the population is $2.14. Find the 90% confidence interval of the true mean. Please include all work showing how you found your answer.

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The heights of adult men in America are normally distributed, with a mean of 69.4 inches and a standard deviation of 2.62 inches. The heights of adult women in America are also normally distributed, but with a mean of 64.3 inches and a standard deviation of 2.51 inches. What percentage of men are SHORTER than 71 inches? Round to nearest tenth of a percent. What percentage of women are TALLER than 64 inches? Round to nearest tenth of a percent.