Question 6.50

6.50 Sample size determination.

Refer to Example 6.3 (page 293) to find the standard deviation of the delay departures for Delta Airlines is given by .

  1. Use the sample size formula (page 311) to determine what sample size you need to have a margin of error equal to two minutes with 90% confidence. Explain why you must always round up to the next higher whole number when using the formula for .
  2. What sample size do you need to have a margin of error equal to two minutes with 95% confidence?