The president of a company that manufactures air conditioners is considering switching his supplier of condensers. SupplierA,the current producer of condensers for the manufacturer, prices its product 5% higher than supplier B does. Because the president wants to maintain his company's reputation for quality, he wants to be sure that supplier B's condensers last at least as long as supplier A's condensers.

After a careful analysis, the president decided to retain supplierAif there is sufficient statistical evidence that supplier A's condensers last longer, on average than supplierB'scondensers. In an experiment, 15 randomly-selected midsize cars were equipped using type-A condensers while another 15 randomly-selected midsize cars were equipped with type-B condensers. The number of kilometers (in thousands) driven by each car before the condenser broke down is displayed in the table below.

SupplierA     SupplierB
156                  109
146                   75
93                    131
152                  131
80                    129
111                  147
107                   78
118                  124
115                   86
125                  127
108                  111
97                    146
142                  114
160                  136
102                   98

Carry out a hypothesis test, at 5% significance level, to determine whether the president should retain Supplier A.