Question

1. 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 is the standard error of the mean?
      
   2. How would the standard error have changed if the sample size had been 100 instead of 25 (assuming that the mean and standard deviations were the same)?
      
   3. How many degrees of freedom would the t-statistic have for this set of data?
      
   4. What would the critical value t* be for a 95% confidence interval with 99 degrees of freedom?
      
   5. What would the margin of error be for a 95% confidence interval for this data (with the sample size of 25)?
      
   6. 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.
      
   7. How would the confidence interval have changed if the standard deviation of the 25 randomly selected customers was 15 instead of 9.84?
      

Answer 1