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.