The report “How Teens Use Media” (Nielsen, June 2009) says that 83% of U.S. teens use text messaging. Suppose you plan to select a random sample of 400 students at the local high school and ask each one if he or she uses text messaging. You plan to use the resulting data to decide if there is evidence that the proportion of students at the high school who use text messaging differs from the national figure given in the Nielsen report. What hypotheses should you test?