a) Construct a 95% confidence interval for the population mean, μ Assume the population has a normal distribution. A sample of 20 part-time workers had mean annual earnings of $3120 with a standard deviation of $677. Round to the nearest dollar.
A few questions I need help with:
a) Construct a 95% confidence interval for the population mean, μ Assume the
population has a
annual earnings of $3120 with a standard deviation of $677. Round to the nearest
dollar.
b) Construct a 98% confidence interval for the population mean, μ Assume the
population has a normal distribution. A study of 14 car owners showed that their
average repair bill was $192 with a standard deviation of $8. Round to the nearest
cent.
c) A doctor at a local hospital is interested in estimating the birth weight of infants.
How large a sample must she select if she desires to be 90% confident that her
estimate is within 2 ounces of the true mean? Assume that s = 5 ounces based on
earlier studies.
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