Aresearcher 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 selects records from 7575 such drivers in 2009 and determines the sample mean bac to be 0.150.15 g/dl with a standard deviation of 0.0700.070 g/dl. ? (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 construct a confidence interval for the mean bac of fatal crashes with a positive bac.

a. 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 normal.

b. 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 mean will be approximately normal.

c. since the distribution of blood alcohol concentrations is normally? distributed, the sample mean will be approximately normal regardless of sample size.

d. since the distribution of blood alcohol concentrations is not normally distributed? (highly skewed? right), the sample mean will be approximately normal regardless of sample size.