confidence intervals

stewardt · #1 $Old$ 11-16-2008, 10:10 PM

In 2000, the mean number of persons per household in Cecil County was 2.71. You would like to see if that figure has changed so you decide to construct a confidence interval. You believe that this variable is not normally distributed, so you take a random sample of n = 50 households in the county. The sample had a mean of Construct a 95% confidence interval for the population mean, following the directions below. Assume the population standard deviation is .

_______________________(a) What is the likely shape of the distribution of this variable, skewed left or skewed right (2 points)?

_______________________(b) What is the formula for E, the margin of error (2 points)?

_______________________(c) What is the value of for your interval (2 points)?

_______________________ (d) What is the value of the margin of error for your interval (2 points).

_______________________ (e) Give the 95% confidence interval (2 points).

please help im not sure about letter a nor b

yvonnehr · #2 $Old$ 11-22-2008, 07:35 PM

your margin of error is the right side of the confidence interval formula. i.e. (either your t or z critical value times s/√n).