Many fast-food restaurants have soft drink dispensers with preset amounts, so that when the operator merely pushes a button for the desired drink the cup is automatically filled. This method apparently saves time and seems to increase worker productivity. To test this conclusion, a researcher randomly selects 18 workers from the fast-food industry, 9 from a restaurant with automatic soft drink dispensers and 9 from a comparable restaurant with manual soft drink dispensers. The samples are independent. During a comparable hour, the amount of sales rung up by the worker is recorded. Assume that α = .01 and that a t test is not appropriate. Test whether workers with automatic dispensers are significantly more productive (higher sales per hour).
Automatic Dispenser ... Manual Dispenser
$153 .......... $105
128 .......... 118
143 .......... 129
110 .......... 114
152 .......... 125
168 .......... 117
144 .......... 106
137 .......... 92
118 .......... 126