3. (40 points) Consider a simultanacous equation model (SEM) as follows: 1/1 = 9271 + 181 + 41, 12 = 1/172 + 12/2 + u2. Assume that 71 = 2, 72 = -0.5, 81 = 3, 82 = 4, u1 = 4v1, u2 = 3v2 and (21, 12, m, 12)' ~ N (0, I4x4). (a) Is this SEM identifiable? Generate a sample of size n=200, 400, 800, respectively, for 1000 times. (b) Estimate the model using 3SLS. Report MAEs and RMSEs of the estimates