The National Sleep Foundation used a survey to determine whether hours of sleeping per night are independent of age (Newsweek, January 19, 2004). The following show the hours of sleep on weeknights for a sample of individuals age 49 and younger and for a sample of individuals age 50 and older.
Hours of Sleep
Age Less than 6 6 to 6.9 7 to 7.9 8 or more Total
49 or younger 30 62 70 78 240
50 or older 37 57 71 95 260
Total 67 119 141 173 500
a.Conduct a test of independence to determine whether the hours of sleep on weeknights are independent of age. Use α = .05.
Compute the value of the χ 2 test statistic (to 2 decimals).