3) To evaluate the effect of a treatment, a sample is obtained from a population (mean = 20). after treatment, the sample mean is found to be 21.3, with a variance (s2) of 9 a) assuming that the sample consists of n = 16, use a 2-tailed hypothesis test with alpha = .05 to determine whether the treatment effect is significant or not. (be sure to calculate the t-statistic and draw a bell-shaped curve with the critical regions highlighted) b) compute cohen's d. Is this is a small, medium, or large effect? c) compute percentage of variance explained (r2). explain what this means in a sentence. d) create a confidence interval with 90% confidence. explain what this means in a sentence. * be sure to answer all questions to receive full credit