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Finding confidence intervals?

BrodyF03

New member
Joined
Nov 21, 2015
Messages
1
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

Elite Member
Joined
Jul 30, 2014
Messages
3,345
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
 
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