Need help with statistics 6

A sample of 170 calls to a customer help line during the week found callers there were kept waiting on average for 19 minutes with s = 9. (a) Find the margin for error for this survey if we use a 95% confidence interval for the length of time all customers during this period are kept waiting. (b) Interpret for management the margin of error. iew b (c) If we only need to be 90% confident, does the confidence interval become wider or narrower? (d) Find the 90% confidence interval. S . . . (a) Margin of Error =] (Round to three decimal places as needed.) (b) Choose the correct answer below. O A. Management can be 95% confident that average waiting time for all callers is within a number of minutes equal to twice the margin of error of the average wait of 19 minutes. O B. Management can be 95% confident that average waiting time for all callers is within a number of minutes equal to the margin of error of the average wait of 19 minutes. O C. Management can be 95% confident that average waiting time for all callers is within a number of minutes equal to half the margin of error of the average wait of 19 minutes. O D. Management cannot make an interpretation of the margin of error. (c) The need to only be 90% confident makes the margin of error because the multiplier (or percentile) that comes from wanting 90% percent confidence and using a t-distribution (or normal model) to describe the sampling distribution is than the multiplier for 95% interval. Thus, the confidence interval becomes (d) The confidence interval is ( .In)