Question

ch 16 #14. (16.25) How heavy a load (pounds) is needed to pull apart pieces of Douglas fir 4 inches long and 1.5 inches square? Here are data from students doing a laboratory exercise: 28464 30504 26638 28032 24621 26240 31525 24002 28437 30454 26615 28007 24588 28875 31442 26984 28411 25083 26592 34428

We are willing to regard the wood pieces prepared for the lab session as an SRS of all similar pieces of Douglas fir. Suppose that the strength of pieces of wood like these follows a Normal distribution with standard deviation 2800 pounds.

Give a 95% confidence interval for the mean load required to pull the wood apart (give your answer with three decimal places).

a. The sample mean is _________(give three decimal places)

b. 95% confidence interval for the mean load is ______to _______.

Answer 1

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FYI I have used R to do this analysis you can do the same even on pen and paper as I have given all the formulas above . The additional thing which you req is z table if you don't have R to find z value at 95% conf level for two tail distribution