Family Incomes A government report on standard of living says that family incomes nationwide are skewed to the right, with a mean of $33,400.
a. We collect income data from a random sample of 50 local families. Why is it okay to use these data for inference even though the population is skewed?
b. The standard deviation of the 50 incomes in our sample was $25,530. Specify the sampling model (shape, center, spread) for the mean income of such samples.
c. This sample of randomly chosen families produced a 90% confidence interval for the
local mean family income of (32,882, 44,761). Does this interval provide evidence that family incomes are unusually high here? Explain briefly.
d. Suppose we hope to improve our estimate by choosing a new sample. How many families must we survey to have 90% confidence of estimating the mean local family income to within $2000?

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The Answer of Family Incomes A government report on standard of living says that family incomes nationwide are skewed to the right, with a mean of $33,400.
a. We collect income data from a random sample of 50 local families. Why is it okay to use these data for inference even though the population is skewed?
b. The standard deviation of the 50 incomes in our sample was $25,530. Specify the sampling model (shape, center, spread) for the mean income of such samples.
c. This sample of randomly chosen families produced a 90% confidence interval for the
local mean family income of (32,882, 44,761). Does this interval provide evidence that family incomes are unusually high here? Explain briefly.
d. Suppose we hope to improve our estimate by choosing a new sample. How many families must we survey to have 90% confidence of estimating the mean local family income to within $2000?

Family Incomes a Government Report on Standard of Living Says