Assuming per group sample size of 20 and a significance level of .05, calculate the power of the equal variances two-sample t-test for the following: (a) Group means of 5 and 10, a common standard deviation of 5. (b) Group means of 20 and 25, a common standard deviation of 5. (c) Group means of 5 and 10, a common standard deviation of 10. (d) Group means of 5 and 12, a common standard deviation of 10. (e) What do these calculations tell you about the relationship between power, group means, effective size and the common standard deviation