Please show all of your work. This is as clear of a photo as I could get. Thank

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Please show all of your work. This is as clear of a photo as I could get. Thank you.

Act4 - Word FILE HOME INSERT DESIGN PAGE LAYOUT REFERENCES MAILINGS REVIEW VIEW Cut AaBbCcl AaBbC AaBbl AaBbC AaBbCcI AaBbCcl A: | Emphasis 1 Heading 11 Heading 21 Heading 4 mes Copy Paste , m Normal! Strong Format Painter Clipboard Font Paragraph Styles 2. A survey of The time period between two versions of computer software is a concern to computer users. 144 computer software packages is conducted. The average time period between two versions is 14 (months) with a s.d. 8 months based on the survey. Test if the actual average time span for a new edition is significantly different from 15 months at = .01 (i)Set up H0 and H1 (ii)Set the decision rule (use z or t based on n, type of test, and value) (iii)Use the sample data summary to compute the test-statistic (observed z or t) as determined in (ii) (iv) Compare the observed test statistics with the decision rule to decide if H0 or H1 should be taken) and provide a statement of interpretation

Explanation / Answer

i.

Formulating the null and alternative hypotheses,              
              
Ho:   u   =   15  
Ha:    u   =/   15   [ANSWER]
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ii.
              
As we can see, this is a    two   tailed test.  
As n = 144 is large, we can use z.  
              
Thus, getting the critical z, as alpha =    0.01   ,      
alpha/2 =    0.005          
zcrit =    +/-   2.575829304      

Hence, we reject Ho when z < -2.576 or z > 2.576. [ANSWER]

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iii.
              
Getting the test statistic, as              
              
X = sample mean =    14          
uo = hypothesized mean =    15          
n = sample size =    144          
s = standard deviation =    8          
              
Thus, z = (X - uo) * sqrt(n) / s =    -1.5   [ANSWER, TEST STATISTIC]      
              
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iv.

As |z| < 2.576, we   FAIL TO REJECT THE NULL HYPOTHESIS.          

Hence, there is no significant evidence that the average time span is diffrent from 15 months. [CONCLUSION]

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