38 A new study has found that, on average, 6- to 12-year-old children are spending less time on household chores today compared to 1981 levels. Suppose two samples representative of the study's results report the following summary statistics for the two periods. 1981 Levels 2008 Levels 2.5 x1 = 26 minutes x2 = 24 minutes points s1 = 4.4 minutes s2 = 3.7 minutes n1 = 30 n2 = 30 00:49:46 Which of the following is the correct value of the test statistic assuming that the unknown population variances are equal? eBook Multiple Choice O z = -1.91 O t58 = 1.91 O z = 1.91 O t59 = -1.91