Ⅰ 搴鋒墭鍒嗗竷鐨勬湡鏈涘拰鏂瑰樊鎬庝箞奼傦紵銆婃傜巼璁哄熀紜鏁欑▼銆嬩範棰
E錛圶n錛=0脳0.5+2脳0.5=1
E錛圶錛=鈭(1~n)E(Xi)/(3^i)=鈭(1~n)1/(3^i)
鈭(1~n)1/(3^i)鏄涓涓絳夋瘮鏁板垪錛屽叕姣1/3,鐢ㄧ瓑姣旀眰鍜屽叕寮忓緱
E(X)=1/2
D(X)=鈭(1~n)D(Xi)/(3^i)²
***VAR琛ㄧず鏂瑰樊錛屾垜涔犳儻鐢―琛ㄧず
D(Xi)=E(Xi²)-(EXi)²
E(Xi²)=4脳0.5=2
D(Xi)=1
D(X)=鈭(1~n)D(Xi)/(3^i)²=鈭(1~n)1/(3^i)²
鈭(1~n)1/(3^i)鏄涓涓絳夋瘮鏁板垪錛屽叕姣1/9,鐢ㄧ瓑姣旀眰鍜屽叕寮忓緱
D(X)=1/8