Consider the twosided confidence interval expression x z al

Consider the two-sided confidence interval expression x - z alpha/2 sigma / square root n

Solution

a)

As

alpha/2 = (1 - confidence level)/2 =    0.01      
Then by table/technology,
  
z(alpha/2) = critical z for the confidence interval =    2.326347874   [ANSWER]

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b)

As

alpha/2 = (1 - confidence level)/2 =    0.1      
Then by table/technology,
  
z(alpha/2) = critical z for the confidence interval =    1.281551566   [ANSWER]

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c)

alpha/2 = (1 - confidence level)/2 =    0.125          
Then by table/technology,

z(alpha/2) = critical z for the confidence interval =    1.15034938   [ANSWER]