HYPOTHESIS TEST QUESTION

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 supplierBdoes. 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

160136

10298

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