1. According to Canadian literature, the mean age at which toddlers first put 2 words together is 19 months, and the standard deviation is 0.33 months. A pediatrician wishes to study whether the mean age may differ from 19 months, by observing toddlers that visit her practice. The pediatrician works one Saturday a month, and one Saturday, she surveys the 6 toddlers who visit her practice by asking their parent(s) at what age their child put first 2 words together; the data are {19.2, 18.1, 17.3, 19.4, 18.4, 18.6} months, and the sample mean is