In 2006, 13.9% of all live births in the United States were to mothers under 20 years of age. A sociologist claims that births to mothers under 20 years of age is decreasing. The sociologist conducts a simple random sample of 38 births and finds that 6 of them were to mothers under 20 years of age. Test the sociologist's claim at the a = 0.1 level of significance. Preliminary: a. Is it safe to assume that n