Need help

6. (20 points) Let fx.Y.Z.T(x, y, z, t) = e (2x+4y+2+2t)/2 x > 0,y > 0, z > 0,t > 0, and =0 otherwise, be the joint PDF of (X, Y, Z, T) (a) Compute 1 - P{X >] and Var[Y - E(Z) | 0 Y =T+ Z >2}