9.229 92 29 Ex. Score: 0.67 of 1 pt 1lWScore: 90.37% (13.56 of 15 pts) 15 of 15
ID: 3155694 • Letter: 9
Question
9.229 92 29 Ex. Score: 0.67 of 1 pt 1lWScore: 90.37% (13.56 of 15 pts) 15 of 15 complete A rescarcher wishes to estimate the average blood alcohol concentration (BAC) for drivers involved in fatal accidents who are found to have positive BAC values. He randomly sclects records from 900 such drivers in 2009 and determines the sample mean BAC to be 0.16 g/dL with a standard deviation of 0.06 g/dl. Complete parts (a) through (d) below (a) A histogram of blood alcohol concentrations in fatal accidents shows that BACs are highly skewed right. Explain why a large sample size is needed to construet a confidence interval for the mean BAC of fatal crashes with a positive BAC OA Since the distribution of blood alcohol concentrations is normally distributed, the sample must be large so that the distribution of the sample mean will be approximately OB Since the distribution of blood alcohol concentrations is not normal. of blood alcobol concentrations is not normally distributed (highly skewed right), the sample mean will be approximately normal regardless of sample size c. Since the distribution of blood alcohol concentrations is not normally distributed (highly skewed right), the sample must be large so that the distribution of the sample mcan will be approximately normal. o Since the distribution of blood alcobol concentrations is normally distributed, the sample mean will be approximately normal regardless of sample size (0b) In 2009, there were approximately 25,000 fatal crasbes in which the driver had a postive BAC Explain why this, along with the fact that the data were obtained using a smple random sample, satisfics the requirements for constructing a confidence interval OA The sample size is greater than 10% of the population. OB The sample sue is less than 10% of the population. The sample size is less than 5%ofthe population. The sample size is greater than 5% of the population. (c) Determine and interpret a 90% confidence interval for the mean BAC in fatal crashes in which the drver had a positive BAC The 90% confidence ttorval for the mean BAC is ( 0.157 .163 ) (Round to the nearest thousandth as needed.) Interpret a 90% confidence interval for the mean BAC. Choose the correct answer below A The researcher is 90% confident that the population mean BAC is m the confidence mer al for drivers mvolve in fatal accidents who have a positive BAC value. There na 90% pro bability that the population mean BAC is m the confidence interval for drivers involved m fatal accidents who have a post ents who have a positive BAC value. Cick to select your answer, then clck Check Answer Clear AlExplanation / Answer
d)
Technically, there is very very very slight chance tha the true mean is less than 0.10, as 0.10 is outside the confidence interval (0.157, 0.163).
So technically, the answer is
OPTION C: Yes, but it is not likely. [ANSWER]
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[The second best answer is OPTION A, as really, it is close to impossible when you calculate it. 0.10 is far from the confidence interval.]
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