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posted by  Jbroncos06balla on 10/5/2008 5:16:20 PM  |  status: Live  

S.E.M. / CI [Part 2] - WILL RATE LIFESAVER IF CORRECT!

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Statistics and Probability N/A N/A N/A
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Could someone please show me how to work this problem?  Please show all steps and work.  Thank you! 

The diameter of the stem of a wheat plant is an important trait because of its relationship to breakage of the stem, which interferes with harvesting the crop. An agronomist measured stem diameter in eight plants of the Tetrastichon cultivar of soft red winter wheat. All observations were made three weeks after flowering of the plant and the mean was found to be 2.275 mm and the standard deviation is 0.238.

 

a) What are the upper and lower limits of the 95% CI for the mean?

 

 

b) Explain in words what this confidence interval means. Explain in the two different ways that were discussed in lecture (i.e. the “95% confidence way” and the “if I took 100 samples…. way):

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posted by "DONALD" on 10/6/2008 1:49:49 PM  |  status: Live
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Response Details:
Given information is An agronomist measured stem diameter in 8(n) plants of the Tetrastichon cultivar of soft red winter wheat. All observations were made three weeks after flowering of the plant and the mean was found to be 2.275(x-bar) mm and the standard deviation is 0.238(s)
The formula for calculating the upper and lower limits of the 95% CI for the mean is given by
Here tα/2,n-1 = t0.05/2, 8-1 = 2.365
Substitute the values we have
 =(2.076, 2.474)
From the above interval we can say that 95% of the values lies in the above interval
 
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