please slove this problem. I got 0.5 for part (a), but I have no idea how to solve part (b) and (c)

{1) You estimate the following ARCH} for the stock returns of 3mm friend's unicorn [pool oat producing company y; = 0.5 + 5:15; "H WNHLO'Q), lE(Et|Qg_1) = U,E(E|Qt_1)= 0'3, 5:2 = ID + D-5E_1. Last period the return was W = 2.5. (a) Calculate the point forecast for yin\". (b) Calculate the point forecast for 0% +1. (c) Find a 95% interval forecast for MT\