Exercise 6.116 introduced a study in which 2006 randomly selected US adults (age 18 or older) were asked to give the number of people in the last six months ‘‘with whom you discussed matters that are important to you.” The average number of close confidants for the full sample was 2.2. In addition, the study asked participants whether or not they had a profile on a social networking site. For the 947 participants using a social networking site, the average number of close confidants was 2.5 with a standard deviation of 1.4, and for the other 1059 participants who do not use a social networking site, the average was 1.9 with a standard deviation of 1.3. Find and interpret a 90% confidence interval for the difference in means between the two groups.

Exercise 6.116

In a recent study, 2006 randomly selected US adults (age 18 or older) were asked to give the number of people in the last six months ‘‘with whom you discussed matters that are important to you.” The average number of close confidants was 2.2, with a standard deviation of 1.4.