For staffing purposes, a retail store manager would like tostandardize the number of checkout lanes to keep open on aparticular shift. She believes that if the standard deviation ofthe hourly customer arrival rates is 9 customers or less, then afixed number of checkout lanes can be staffed without excessivecustomer waiting time or excessive clerk idle time. However, beforedetermining how many checkout lanes (and thus clerks) to use, shemust verify that the standard deviation of the arrival rates doesnot exceed 9. Accordingly, a sample of 25 hourly customer arrivalrates was compiled for that shift over the past week.
a. Select the hypotheses to test whether thestandard deviation of the customer arrival rates exceeds9.
H0: ?2 ? 81;HA: ?2 > 81
H0: ?2 = 81;HA: ?2 ? 81
H0: ?2 ? 81;HA: ?2 < 81
b. Calculate the value of the test statistic.Assume that customer arrival rates are normally distributed.(Round intermediate calculations to at least 4 decimalplaces and final answer to 3 decimal places.)
Test Statistic: ???
| Hourly Arrival Rates |
| 122 |
| 122 |
| 101 |
| 119 |
| 91 |
| 115 |
| 112 |
| 111 |
| 118 |
| 124 |
| 122 |
| 122 |
| 124 |
| 122 |
| 121 |
| 125 |
| 116 |
| 93 |
| 124 |
| 105 |
| 132 |
| 93 |
| 121 |
| 112 |
| 114 |
