The following equation is for a multiplicative seasonal model of the type ARIMA(p,d,q)x(P,D,Q)4. Y₁ 0.5Y1+Y4-0.5 Yts +e-0.3.1 (a) What are the values of p, d, q, P, D and Q (b) Write the characteristic polynomial of autoregressive (AR) part of the model. (c) Compute the roots of the polynomial in part b and discuss invertibility/causality conditions of the model. THE END