1.设随机变量X~B(10,0.2),则E(X)= ? 2.设随机变量X~U(1.7),则D 设随机变量服从X?103P0.70.20.1,则E(X)=
\u8bbe\u968f\u673a\u53d8\u91cfX~B(15,0.2),\u5219E(3X)=3*15*0.2=9 \u9700\u8981\u89e3\u91ca\u5417
\u56e0\u4e3a\u968f\u673a\u53d8\u91cf\u670d\u4eceX?103P0.70.20.1\uff0c\u6240\u4ee5E\uff08X\uff09=\uff08-1\uff09\u00d70.7+0\u00d70.2+3\u00d70.1=0.4D\uff08X\uff09=E\uff08X2\uff09-E\uff08X\uff092=\uff08-1\uff092\u00d70.7+02\u00d70.2+32\u00d70.1-\uff080.4\uff092=1.44\uff0e\u6545\u7b54\u6848\u4e3a\uff1a-0.4\uff0c1.44\uff0e
1、E(X)=np=10·0.2=2
2、
D(X)=(b-a)^2/12
=36/12
=3
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绛旓細闅忔満鍙橀噺X~B(10,0.8)锛屽垯闅忔満鍙橀噺10-X~B(10,0.8)銆備粠鍚箟涓婅锛孹琛ㄧず10娆¤瘯楠屼腑鏌愪簨浠禔鍙戠敓鐨勬鏁帮紝鑰10-X琛ㄧず10娆¤瘯楠屼腑浜嬩欢A涓嶅彂鐢熺殑娆℃暟銆
绛旓細銆愮瓟妗堛戯細A 姝f闅忔満鍙橀噺X鐨勮娴嬪艰惤鍦ㄨ窛鍧囧肩殑璺濈涓1鍊嶆爣鍑嗗樊鑼冨洿鍐呯殑姒傜巼绾︿负0锛68锛屾鎬侀殢鏈哄彉閲廥鐨勮娴嬪艰惤鍦ㄨ窛鍧囧肩殑璺濈涓2鍊嶆爣鍑嗗樊鑼冨洿鍐呯殑姒傜巼绾︿负0锛95锛岃岃惤鍦ㄨ窛鍧囧肩殑璺濈涓3鍊嶆爣鍑嗗樊鑼冨洿鍐呯殑姒傜巼绾︿负0锛9973銆
绛旓細EX=10*0.1=1 DX=10*0.1*(1-0.1)=0.9
绛旓細鈭璁鹃殢鏈哄彉閲廥锝B锛10锛0.8锛夛紝 鈭碊X=10脳0.8锛1-0.8锛=1.6锛 鈭碊锛2X+1锛=2 2 脳1.6=6.4 鏁呴塁锛
绛旓細(1)璁句簨浠禔銆丅鐩镐簰鐙珛锛孭锛圓UB锛=0.6锛孭锛圓锛=0.4锛屽垯 P(AUB)=P(A)+P(B)-P(A)P(B)0.6=0.4+P(B)-0.4P(B)0.6P(B) = 0.2 P(B) = 1/3 (2)璁鹃殢鏈哄彉閲廥~B锛400锛0.1锛夛紝D(X)=np(1-p) = 400(0.1)(1-0.1) = 36 (3)X~U锛1锛4锛塜鐨勫瘑搴﹀嚱鏁 f(...
绛旓細瀵逛簬浜岄」鍒嗗竷X~B锛坣,p锛,鍏舵湡鏈汦X=np,鏂瑰樊DX=np(1-p)鎵浠闅忔満鍙橀噺X~B(100,0.05),鍒檟鐨勬柟宸槸锛100脳0.05脳(1-0.05)=4.75 绛旀锛4.75
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绛旓細鈻=X^2-4鈮0 X鈮2锛屾垨X鈮わ紞2 鍙闅忔満鍙橀噺X~U锛0锛10锛夋晠鏈夊疄鏍圭殑姒傜巼鏄(10-2)/10=0.8 2銆丄銆B銆丆涓嚦灏戞湁涓涓彂鐢熺殑姒傜巼 锛漃锛圓锛婤锛婥锛夛紳P锛圓锛夛紜P锛圔锛夛紜P锛圕锛夛紞P锛圓B锛夛紞P锛圔C锛夛紞P锛圕A锛+P锛圓BC锛夛紳1/4+1/4+1/2-1/8 锛7/8 P锛圔C锛=P锛圕A锛=0璇存槑P锛...