X 1 2 3-|||-p .-1 .https:/img.zuoyebang.cc/zyb_9e778ee622bfcbd85bc2aaa7e97331dd.jpg-theta .https:/img.zuoyebang.cc/zyb_9e778ee622bfcbd85bc2aaa7e97331dd.jpg-20-|||-其中θ未知,现取得一组样本值:1,1,1,3,2,1,3,2,则θ的矩估计值为-|||-__-|||-(A) dfrac (31+sqrt {97)}(48)-|||-B ) dfrac (9)(20)-|||-(C) dfrac (31+sqrt {97)}(48) 或 dfrac (31-sqrt {97)}(48)-|||-(D) dfrac (31-sqrt {97)}(48)