设随机变量X~N(2,4),Y=2X+3是由X生成的一个新的随机变量,则P{Y=2}= 已知随机变量X~B(n,p),若E(X)=4,Y=2X+3,...
\u8bbe\u968f\u673a\u53d8\u91cfX,Y\u76f8\u4e92\u72ec\u7acb\uff0cX~N(1,2),Y~N(3,4)\u5219P{X+Y\u22644}=\u8fd9\u9053\u9898\u6211\u518d\u6982\u7387\u8bba\u4e0e\u6570\u7406\u7edf\u8ba12018\u5e744\u6708\u8003\u8bd5\u771f\u9898\u4e0a\u770b\u5230\u3002\u9887\u8003\u8ba1\u7b97\u3002\u770b\u4e86\u7b54\u6848\u662f0.5\u3002\u4f46\u6211\u7684\u7b54\u6848\u548c\u5b83\u4e0d\u4e00\u6837\uff0c\u4f46\u6b65\u9aa4\u80af\u5b9a\u662f\u5bf9\u7684\u3002
\u89e3\uff1a\u56e0\u4e3a\u76f8\u4e92\u72ec\u7acb\uff0cX~N(1,2),Y~N(3,4)\uff0c\u6240\u4ee5\u53ef\u77e5\uff0cX+Y~N(4,6)\u3002\u6240\u4ee5\u6211\u4eec\u6839\u636e\u4e0b\u9762\u7684\u516c\u5f0f\uff0c\u53ef\u4ee5\u5f97\u5230\u5bf9\u5e94\u7684X+Y\u7684\u6982\u7387\u5206\u5e03\u51fd\u6570\uff1a
\u6211\u4eec\u8bbeZ=X+Y\uff0c\u6240\u4ee5:
\u4ee5\u6b64\u6211\u4eec\u53ef\u4ee5\u77e5\u9053\u5bf9\u5e94\u7684\u5206\u5e03\u51fd\u6570\uff1a
\u7684\u79ef\u5206\u4e3a
\u6700\u540e\uff0cP{X+Y\u22644} = F(4) \u3002\u6211\u4eec\u5c06z=4\u4ee3\u5165\u540e\uff0c\u5f97\u51fa
\u4f46\u6b63\u786e\u7b54\u6848\u4e3a0.5\u3002\u6211\u8fd9\u4e2a\u548c\u5b83\u662f\u6709\u51fa\u5165\u7684\u3002\u4f46\u6211\u575a\u4fe1\u6211\u7684\u6b65\u9aa4\u80af\u5b9a\u662f\u5bf9\u7684\u3002\u5982\u6709\u758f\u5ffd\u9519\u8bef\u7684\u5730\u65b9\uff0c\u5e0c\u671b\u53ef\u4ee5\u544a\u77e5\u3002\u6211\u4e5f\u5f88\u56f0\u60d1
\u4f60\u597d\uff01\u53ef\u5982\u56fe\u5148\u6c42\u51fan\u548cp\uff0c\u518d\u8ba1\u7b97\u6982\u7387\u3002\u7ecf\u6d4e\u6570\u5b66\u56e2\u961f\u5e2e\u4f60\u89e3\u7b54\uff0c\u8bf7\u53ca\u65f6\u91c7\u7eb3\u3002\u8c22\u8c22\uff01
绛旓細浠=2X+3Y-1,鍒橺~N(0锛25),鎵浠(|2X+3Y-1|<=9.8)=2P(0<2X+3Y-1<=9.8)=2P(0<Z<=9.8)=2P(0<Z/5<=9.8/5)(鏍囧噯鍖)=2{&(1.96)-&(O)}=2(0.95-0.5)=0.9.鍏朵腑&琛ㄧず鏍囧噯姝f佸垎甯冭礋鏃犵┓鍒版嫭鍙峰唴鏁板瓧鐨勬潕鏇肩Н鍒嗐備功涓婇偅涓鍙蜂笉浼氭墦 ...
绛旓細N锛2,4锛鏄寚x鏈嶄粠渭 = 2锛屜 = 2鐨勬鎬佸垎甯冦備篃灏辨槸璇寸洿绾縳=2鏄姝f佸垎甯冨浘鍍忕殑瀵圭О杞达紝鎵浠ワ紝P锝沊鈮2锝=1/6銆傝嫢闅忔満鍙橀噺X鏈嶄粠涓涓暟瀛︽湡鏈涗负渭銆佹柟宸负蟽^2鐨勬鎬佸垎甯冿紝璁颁负N(渭锛屜僞2)銆傚叾姒傜巼瀵嗗害鍑芥暟涓烘鎬佸垎甯冪殑鏈熸湜鍊嘉煎喅瀹氫簡鍏朵綅缃紝鍏舵爣鍑嗗樊蟽鍐冲畾浜嗗垎甯冪殑骞呭害銆傚綋渭 =...
绛旓細杩炵画鍑芥暟锛屽湪鍗曠偣鐨勬鐜囧间竴寰嬩负0.
绛旓細璁綵=(X-2)/2 鍒欙紝Z~N(0锛1)P(X鈮0)=P(Z鈮-1)=桅(-1)=1-桅(1)=1-0.8413 =0.1587
绛旓細瑙o細E(ax+b)=a*E(x)+b=2a+b=0锛汥(ax+b)=a^2*D(x)=4a^2=1锛涙晠a=1/2锛b=-1 鎴 a=-1/2锛宐=1 鏂瑰樊鍏紡鏄竴涓暟瀛﹀叕寮忥紝鏄暟瀛︾粺璁″涓殑閲嶈鍏紡锛屽簲鐢ㄤ簬鐢熸椿涓悇绉嶄簨鎯咃紝鏂瑰樊瓒婂皬锛屼唬琛ㄨ繖缁勬暟鎹秺绋冲畾锛屾柟宸秺澶э紝浠h〃杩欑粍鏁版嵁瓒婁笉绋冲畾銆
绛旓細a=2 x灞炰簬姝f佸垎甯冿紝姝f佸垎甯冪殑姒傜巼瀵嗗害鏄互鐩寸嚎x=渭瀵圭О鐨勶紝杩欓噷渭=2 P锛圶>a)=0.5锛屾墍浠鍒氬ソ鏄湪渭杩欎釜鐐癸紝鎵浠=2
绛旓細鐩镐簰鐙珛鐨勬鎬佸垎甯冪殑绾挎у嚱鏁颁粛鐒舵湇浠庢鎬佸垎甯冿紝鐢变簬E(2X-Y)=2EX-EY=2脳1-2=0,D(2X-Y)=4DX+DY=4脳25+4=104锛屾墍浠2X-Y~N(0,104)銆
绛旓細2011-02-01 璁綳~N(1,2),Y鏈嶄粠鍙傛暟涓3鐨勬硦鏉惧垎甯,涓擷涓嶻鐙珛,... 165 2015-08-23 璁鹃殢鏈哄彉閲廥鏈嶄粠鍙傛暟涓(2,p)鐨勪簩椤瑰垎甯,闅忔満鍙橀噺Y鏈嶄粠鍙... 37 2015-01-12 姒傜巼缁熻闂,4銆佽闅忔満鍙橀噺X鏈嶄粠鍙傛暟涓2鐨勬硦鏉惧垎甯冦傝Y=... 68 2016-10-29 璁鹃殢鏈哄彉閲弜鏈嶄粠鍙傛暟涓3鐨勬硦鏉惧垎甯,闅忔満鍙橀噺Y~N...
绛旓細姹傚嚭杩欎竴鍒嗗竷鐨勪袱涓弬鏁板嵆鍙闅忔満鍙橀噺X锝濶锛-3锛1锛夛紝Y锝N锛2锛1锛夛紝涓擷涓嶻鐩镐簰鐙珛鈭碯=X-2Y+7涔熸湇浠庢鎬佸垎甯冨張鐢变簬EZ=E锛圶-2Y+7锛=E锛圶锛-2E锛圷锛+E锛7锛=-3-2•2+7=0锛孌锛圶-2Y+7锛=D锛圶锛+锛-2锛2D锛圷锛+D锛7锛=1+4+0=5鈭碯锝濶锛0锛5锛夈
绛旓細棣栧厛锛岃c涓哄父鏁帮紝鍒橢(c) = c锛孌(c) = 0銆傜劧鍚庤鐭ラ亾X~N(-3,1)鐨勬剰鎬濇槸X鏈嶄粠鏈熸湜涓-3锛屾柟宸负1鐨勬鎬佸垎甯冿紝鍗矱(X) = -3锛孌(X) = 1銆傚悓鐞嗭紝E(Y) = 2锛D(Y) = 4銆傛墍浠ワ細E(Z) = E(X-2Y+5) = E(X) - 2E(Y) +E(5) = -2 鍥犱负X銆乊鐩镐簰鐙珛锛屾墍浠(Z) =...