題組內容

3.

(d) \( (10\%) \) Let \( Z_{1} = \tilde{X}_{1} + \tilde{X}_{2}, Z_{2} = \tilde{X}_{3} \) and \( Z_{3} = \tilde{X}_{4} \). Find the joint distribution of \( (Z_{1}, Z_{2}, Z_{3}) \).