A histogram of ZIP-code income is skewed right. Why do you suppose this is? If ZIP-code income is skewed right, can it also be normally distributed? If ZIP-code income is not normally distributed, is this an important problem for the calculations made in Exercises 6.22 and 6.23?

Exercises 6.22

Data were obtained for 16,405 women who immigrated to the United States and their adult daughters at matching times of their lives [5]. The median income in the mothers’
and daughters’ ZIP codes were used to measure economic status. Consider this database to be a population, from which a random sample of 25 mothers was selected with these ZIP-code incomes. Calculate a 95 percent confidence interval for the population mean. Does your confidence interval include the actual value of the population mean, μ = 37,408?

Exercises 6.23

The following data are the median ZIP-code incomes of the daughters of the random sample of 25 mothers in the preceding exercise. Calculate a 95 percent confidence interval for the population mean. Does your confidence interval include the actual value of the population mean, μ = 40,064?

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32,644 39,225 33,445 45,267 33,656 26,505 22,091 47,806 49,686 39,747 22,151 36,566 36,769 26,505 29,872 24,207 28,651 30,174 41,621 46,342 23,498 39,906 53,881 39,225 46,468