Consider the following data drawn independently from normally distributed populations: (You may find it useful to reference the appropriate table: z table or t table) X1 = -1.6 x2 = -16.3 2 = 8.9 2 2 = 7.9 n1 = 23 n2 = 15 a. Construct the 95% confidence interval for the difference between the population means. Assume the population variances are unknown but equal. (Round final answers to 2 decimal places.) Confidence interval is to