9. One sample has it = 15 with 55 = 1600, and a second Sample has nf - 15 with 55 - 1700 n. Find the pooled variance for the two samples.

b. Compute the estimated standard endir for the sample mean difference

c. If the sample mean difference is 8 points, is this enough to reject the mall hypothesis and conclude that there is a significant difference for a two-tailed test ant the 05 level!

d. If the sample mean difference is 12 points, is this.

enough to indicate a significant difference for a two-tailed bost at the 05 level?

e. Calculate the percentage of variance accounted for

(2 ) to measure the effect size for as B-point meant difference and for a 12-point mean difference