<s>[INST] A sports equipment store sells a certain type of racket. A given model is designed to last for 5 years. However, the store's supplier has offered a new model that is supposed to last for 7 years. The store owner believes that this new model will increase the average time a customer keeps a racket by 1.4 years. The store owner wants to know if this new model will actually increase the average time a customer keeps a racket by 1.4 years. To test this, the store owner will randomly select a group of customers who buy the new model racket and keep track of how long they keep their rackets. If the null hypothesis that the average time a customer keeps a racket is 5.5 years (i.e., H0: mu = 5.5) is not rejected, the store owner will conclude that the new model does not increase the average time a customer keeps a racket by 1.4 years.[/INST]