The mean age of all 638 used cars for sale in the Ventura Country Star one Saturday in 2013 was 7.9 years, with a standard deviation of 7.7 years. The distribution of ages is right-skewed. For a study to determine the reliability of classified ads, a reporter randomly selects 40 of these used cars and plans to visit each owner to inspect the cars. He finds that the mean age of the 40 cars he samples is 8.2 years and the standard deviation of those 40 cars is 6.0 years.
a. Which of these four numerical values are parameters and which are statistics?
b. µ =? σ =? s =? x-bar =? x-bar =?
c. Are the conditions for using the CLT fulfilled? What would be the shape of the approximate sampling distribution of a large number of means, each from a sample of 40 cars?