Data from the Bureau of Labor Statistics’ Consumer ExpenditureSurvey (CE) show that annual expenditures for cellular phoneservices per consumer unit increased from $237 in 2001 to $634 in2007. Let the standard deviation of annual cellular expenditure be$52 in 2001 and $207 in 2007.
What is the probability that the average annual expenditure of125 cellular customers in 2001 exceeded $220? (Round“z” value to 2 decimal places, and final answer to 4decimal places.) |
| b. | What is the probability that the average annual expenditure of125 cellular customers in 2007 exceeded $607? (Round“z” value to 2 decimal places, and final answer to 4decimal places.) |
