A poll used a sample of 100 randomly selected car owners. Within the? sample, the mean time of ownership for a single car was 6.20 years with a standard deviation of 3.62 years. Test the claim by the owner of a large dealership that the mean time of ownership for all cars is less than 6.5 years. Use a 0.05 significance level. State the null and alternative hypotheses. Find the? z-score.