OpenStudy (sabasattar):

A statistics instructor randomly selected four bags of oranges, each bag labeled 10 pounds, and weighed the bags. They weighed 10.4, 10.7, 10.3, and 10.8 pounds. Assume that the distribution of weights is Normal. Find a 95% confidence interval for the mean weight of all bags of oranges. Use technology for your calculations. What are the lower and upper bounds of this confidence interval?

11 months ago
OpenStudy (lgnd_88):

The CI is calculated using the formula x-bar +/- t-alpha/2 * sigma / sqrt(n) x-bar is the average of the numbers = 9.525 sigma is the standard deviation of the numbers = 0.15 Since there are a small number of samples you have to use the student t distribution to calculate t-alpha /2. The number of samples is 4, so the degrees of freedom is 3. You want a 95% CI. Using the table at the web site http://www.sjsu.edu/faculty/gerstman/Sta... t-alpha/2 is 3.182 So the CI is 9.525 +/- 3.182 * 0.15 / sqrt(4) = (9.29, 9.76)

11 months ago
OpenStudy (lgnd_88):

Hope that helps^^

11 months ago
OpenStudy (sabasattar):

Thank you so much!

11 months ago