# Thread: confidence intervals

1. ## confidence intervals

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

2. ## margin of error

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).