6. Gravetter/Wallnau/Forzano, Essentials - Chapter 10 - End-of-chapter question 6 Two separate samples receive different treatments. After treatment, the first sample has n = 6 with SS = 236, and the second has n = 12 with SS = 340. The pooled variance for the two samples is Compute the estimated standard error for the sample mean difference. Estimated S(M1 - M2) = If the sample mean difference is 7 points, is this enough to reject the null hypothesis and conclude that there is a significant difference for a two-tailed test at the .05 level? t-critical rt O Reject the null hypothesis; there is a significant difference. O Fail to reject the null hypothesis; there is no significant difference. O Fail to reject the null hypothesis; there is a significant difference. O Reject the null hypothesis; there is no significant difference