Solution
= Solution
By <Gaussian conditional expectation>,
$$
E[Y\mid S_1]=E(Y)+\operatorname{cov}(Y,S_1)V^{-1}(S_1-\mu).
$$
Multiply by $U'(X_0)$, take expectations, and use part (c):
$$
\frac{E[U'(X_0)S_1]}{E[U'(X_0)]}=(1+r)S_0.
$$
Substitution into part (d) gives
$$
\boxed{\pi_0(Y)=\frac1{1+r}\left[E(Y)-(\mu-(1+r)S_0)^TV^{-1}
\operatorname{cov}(S_1,Y)\right].}
$$