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A survey of 25 randomly selected customers found that their average age was 31.84 years with...

A survey of 25 randomly selected customers found that their average age was 31.84 years with a standard deviation of 9.84 years.

  1. What would the critical value t* be for a 95% confidence interval with 99 degrees of freedom?
  2. What would the margin of error be for a 95% confidence interval for this data (with the sample size of 25)?
  3. Construct a 95% confidence interval for the mean age of all customers for this data (with the sample size of 25) assuming that all conditions and assumptions have been met for the confidence interval.
  4. How would the confidence interval have changed if the standard deviation of the 25 randomly selected customers was 15 instead of 9.84?
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Answer #1

tion :- a) q=0.05 dot = gg tcritical - 1.984 by Margin of error tn 1,912 에g = 2.069 x 9.84 125 = 4.06 C) 95% considence inter

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