Problem 4 25 pts] Suppose x1, . . ., 21 are 21 random samples from N(M, 62), and the data are 0.64, -2.25, 0.86, 1.02, 0.53, 0.86, -0.46, -2.86, -0.16, 0.37, 1.24, 2.11, 0.42, -0.25, -0.22, 0.41, 0.01, -0.30, -0.69, -0.83, 0.04 (a). If both u and o' are unknown, construct an EXACT 95% confidence interval for M. (b). If o = 1.1, construct an EXACT 95% confidence interval for /