Need help with a statistics question

Statistics
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We are evaluating the sheet metal scrap rate in a contractor proposal. Based on a sample of 24 parts you calculate a mean rate of 6.50% (treat as 6.50) and a standard deviation of 1.20. Calculate a 80% confidence interval to be used to support negotiations. (Carry intermediate calculations to three decimal places.)

6.08 ≤ μ ≤ 6.92

6.41 ≤ μ ≤ 6.59

6.43 ≤ μ ≤ 6.57

6.18 ≤ μ ≤ 6.82          

Jun 16th, 2015

Thank you for the opportunity to help you with your question!

Standard error of the mean will be
1.20/sqrt(23) = 0.2502
Using a t-distribution table, look up 23 degrees of freedom.
The number of standard errors associated with a "tail" of 0.10 or "two tails" of 0.20 is 1.319.
1.319*0.2502 = 0.3300

Hence, the 80% confidence interval is
from 6.17 to 6.83 (percent scrap rate)


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Jun 16th, 2015

That answer is not one of the choices I posted to choose from

Jun 16th, 2015

boy its calculation of points so it is aproximate but the ans is option d you can caculate points wise

Jun 16th, 2015

boy its calculation of points so it is aproximate but the ans is option d you can caculate points wise

Jun 16th, 2015

it can give you the main theme

Jun 16th, 2015

it can give you the main theme

Jun 16th, 2015

Okay thank you very much for your time and help.  Have a great day!

Jun 16th, 2015

Okay thank you very much for your time and help.  Have a great day!

Jun 16th, 2015

welcome................................

Jun 16th, 2015

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