An investigator wants to show that first-born children score higher on iq tests than second-borns. he takes a simple random sample of 400 two-child families in a school district, both children being enrolled in elementary school. he gives these children the wisc vocabulary test, with following results: the 400 first-borns average 29 and their sd is 10. the 400 second-borns average 28 and their sd is 10. does the result support the research hypothesis?