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BrodyF03
11-21-2015, 11:22 PM
Past experience indicates that the breaking strength of yarn used in manufacturing drapery material is normallydistributed and that σ = 2 psi. A random sample of 15 specimens is tested and the average breaking strengthis found to be x = 97.5 psi.
(a) Find a 95% confidence interval on the true mean breaking strength.
(b) Find a 99% confidence interval on the true mean breaking strength

Ishuda
11-22-2015, 12:01 PM
Past experience indicates that the breaking strength of yarn used in manufacturing drapery material is normallydistributed and that σ = 2 psi. A random sample of 15 specimens is tested and the average breaking strengthis found to be x = 97.5 psi.
(a) Find a 95% confidence interval on the true mean breaking strength.
(b) Find a 99% confidence interval on the true mean breaking strength

What are your thoughts? What have you done so far? Please show us your work even if you feel that it is wrong so we may try to help you. You might also read
http://www.freemathhelp.com/forum/threads/78006-Read-Before-Posting

If you need a review, this page may help "Hypothesis Testing for a Mean"
https://onlinecourses.science.psu.edu/stat200/node/54