Ahypothesis regarding the weight of newborn infants at a community hospital is that the mean is 6.6 pounds. a sample of seven infants is randomly selected and their weights at birth are recorded as 9.0, 7.3, 6.0, 8.8, 6.8, 8.4, and 6.6 pounds. what is the decision for a statistical significant change in average weights at birth at the 5% level of significance? rev: 04_14_2015_qc_cs-13524 reject the null hypothesis and conclude the mean is lower than 6.6 lb. fail to reject the null hypothesis. cannot calculate because the population standard deviation is unknown. reject the null hypothesis and conclude the mean is higher than 6.6 lb.