12.2 One sample has n = 15 with SS = 1570, and a second sample has n = 15 with SS = 1650. a. Find the pooled variance for the two samples. b. Compute the estimated standard error for the sample mean differences (i.e. for the two groups). c. If the sample mean difference (i.e. M1 - M2) is 8 points, is this enough to indicate a significant difference for a two-tailed test at = .05 level? d. If the sample mean difference (i.e. M1 - M2) is 12 points, is this enough to indicate a significant difference for a two-tailed test at = .05 level? (Note) be sure and show a full diagram of the research design. Also show all steps and calculations you made for each test following the process outlined in the t-test formula sheet handout. What statistical decision do you make in each case