3. a random sample of 100 records in a us city during the past year showed an average life span of 71.8 years. a. assuming normality and a population standard deviation of 8.9 years, does this seem to indicate that the mean life span today is not different than 70 years ? use a 0.10 level of significance and write hypothesis testing steps explicitly. b. find the p-value that corresponds to the test statistic. would you reject h0 by using the p-value? why ?