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16. A recent study of 20 individuals found that the average number of therapy sessions these persons required to recover from shoulder surgery was 9.6 , with a standard deviation of 2.8 . A separate study of 25 individuals found that the average number of sessions these persons required to recover from hip surgery was 10.3 , with a standard deviation of 2.3 . Assume the population variances are not equal. At a = 0.01, is there a statistically significant difference in the sample means? Show all steps of the hypothesis test you conduct