什么叫分布列和数学期望值 分布列和数学期望怎么做
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分布列就是把事件的情况跟概率总结到一个表中.这个表就是分布列....期望就是按照事件乘以概率来计算的一种理想结果..
绛旓細鍒嗗竷鍒楀氨鏄竴涓鐜囬鎵鏈変簨浠舵瀬鍏舵鐜囧垪鎴愮殑涓よ涓ゅ垪鐨勮〃鏍笺 鏁板鏈熸湜灏辨槸鎶婃鐜囦箻浠ュ搴旂殑鏁板瓧鍗冲彲锛屾瘮濡傝纭竵鍚戜笂涓1锛屽悜涓嬩负0锛孍锛堟姇纭竵锛=1/2*1+1/2*0=1/2
绛旓細鍒嗗竷鍒楋紝琛ㄧず姒傜巼鍦ㄦ墍鏈夌殑鍙兘鍙戠敓鐨勬儏鍐典腑鐨勫垎甯銆傚湪姒傜巼璁哄拰缁熻瀛︿腑锛屼竴涓鏁ｆч殢鏈哄彉閲忕殑鏈熸湜鍊兼槸璇曢獙涓瘡娆″彲鑳界粨鏋滅殑姒傜巼涔樹互鍏剁粨鏋滅殑鎬诲拰銆傛湡鏈涘兼槸闅忔満璇曢獙鍦ㄥ悓鏍风殑鏈轰細涓嬮噸澶嶅娆＄殑缁撴灉璁＄畻鍑虹殑绛夊悓鈥滄湡鏈涒濈殑骞冲潎鍊笺傞渶瑕佹敞鎰忕殑鏄紝鏈熸湜鍊煎苟涓嶄竴瀹氱瓑鍚屼簬甯歌瘑涓殑鈥滄湡鏈涒濓紝鈥滄湡鏈涘尖濅篃璁镐笌姣...
绛旓細绂绘暎鍨嬮殢鏈哄彉閲忕殑涓鍒囧彲鑳界殑鍙栧紉i涓庡搴旂殑姒傜巼P(=xi)涔嬬Н鐨勫拰绉颁负鐨鏁板鏈熸湜锛堣绾ф暟缁濆鏀舵暃锛夛紝璁颁负E銆傚鏋滈殢鏈哄彉閲忓彧鍙栧緱鏈夐檺涓笺傞殢鏈哄彉閲忔渶鍩烘湰鐨勬暟瀛︾壒寰佷箣涓銆傚畠鍙嶆槧闅忔満鍙橀噺骞冲潎鍙栧肩殑澶у皬銆傚張绉版湡鏈涙垨鍧囧笺傚畠鏄畝鍗曠畻鏈钩鍧囩殑涓绉嶆帹骞匡紝绫讳技鍔犳潈骞冲潎銆
绛旓細1銆佸垎甯冨垪锛氬垎甯冨垪鐢ㄤ簬鎻忚堪绂绘暎鍨嬮殢鏈哄彉閲忕殑鍙栧煎強鍏跺搴旂殑姒傜巼銆傚浜庝竴涓鏁ｅ瀷闅忔満鍙橀噺X锛屽叾鍒嗗竷鍒楀垪鍑轰簡鎵鏈夊彲鑳界殑鍙栧紉鍜岀浉搴旂殑姒傜巼P(X=x)銆傚垎甯冨垪閫氬父浠ヨ〃鏍肩殑褰㈠紡鍛堢幇锛屾柟渚胯绠楀拰鍒嗘瀽鍚勪釜鍙栧肩殑姒傜巼銆傚垎甯冨垪鐨勭壒鐐规槸姒傜巼闈炶礋涓旀鐜囦箣鍜屼负1銆2銆佹暟瀛︽湡鏈涘叕寮忥細鏁板鏈熸湜鏄弿杩伴殢鏈哄彉閲忓钩鍧囧彇鍊肩殑涓...
绛旓細鏁板鏈熸湜锛圗xpectation锛夋槸姒傜巼璁轰腑鐢ㄦ潵琛￠噺闅忔満鍙橀噺骞冲潎鍙栧肩殑鎸囨爣銆傚浜庣鏁ｉ殢鏈哄彉閲忥紝鏁板鏈熸湜鏄叾鍙兘鍙栧间笌瀵瑰簲姒傜巼鐨勪箻绉殑鎬诲拰銆傛暟瀛︽湡鏈涚殑鎰忎箟鍦ㄤ簬瀹冨彲浠ヨ〃绀洪殢鏈哄彉閲忓湪澶ч噺閲嶅璇曢獙涓钩鍧囧彇寰楃殑鍊笺傚畠鏄竴涓闅忔満鍙橀噺鐨勫钩鍧囨ц川杩涜搴﹂噺鐨勫伐鍏枫傞氳繃璁＄畻鏁板鏈熸湜锛屾垜浠彲浠ヨ幏寰楅殢鏈哄彉閲忓钩鍧囧彇鍊肩殑棰勬湡缁撴灉...
绛旓細鍒嗗竷鍒锛圥robability Mass Function锛孭MF锛夋槸姒傜巼璁轰腑鐢ㄦ潵鎻忚堪绂绘暎鍨嬮殢鏈哄彉閲忓彇鍊肩殑姒傜巼鍒嗗竷鐨勫嚱鏁般傚浜庣鏁ｅ瀷闅忔満鍙橀噺 X锛屽叾鍒嗗竷鍒楀彲浠ヨ〃绀轰负 P(X = x)锛屽叾涓 x 琛ㄧず闅忔満鍙橀噺鍙兘鍙栧埌鐨勬煇涓彇鍊笺傚垎甯冨垪缁欏嚭浜嗛殢鏈哄彉閲忓彇鍚勪釜鍙兘鍙栧肩殑姒傜巼銆鏁板鏈熸湜锛圡athematical Expectation锛夛紝涔熺О涓哄钩鍧囧兼垨鏈熸湜...
绛旓細鍒嗗竷鍒锛圥robability mass function, PMF锛夋槸姒傜巼璁轰腑鐢ㄤ簬鎻忚堪绂绘暎闅忔満鍙橀噺鐨勬鐜囧垎甯冪殑鍑芥暟銆傚浜庣鏁ｉ殢鏈哄彉閲 X锛屽叾鍒嗗竷鍒楃粰鍑轰簡姣忎釜鍙兘鍙栧 x 鍙戠敓鐨勬鐜 P(X=x)銆鏁板鏈熸湜锛圗xpected value锛夋槸姒傜巼璁轰腑鐢ㄤ簬琛￠噺闅忔満鍙橀噺骞冲潎鍊肩殑涓涓寚鏍囥傚浜庝竴涓鏁ｉ殢鏈哄彉閲 X锛屽叾鏁板鏈熸湜 E(X) 瀹氫箟涓烘寜鐓ф鐜...
绛旓細鈭玿*f(x)dx锛屽嵆闅忔満鍙橀噺X鍦ㄦ暣涓彇鍊艰寖鍥翠笂鐨勬鐜囧瘑搴﹀嚱鏁颁笌鍏跺彇鍊肩殑涔樼Н鐨勭Н鍒嗐傛暟瀛︽湡鏈涘湪杩欑鎯呭喌涓嬪彲浠ョ悊瑙ｄ负瀵硅繛缁瀷闅忔満鍙橀噺X鎵鏈夊彲鑳藉彇鍊肩殑鍔犳潈绉垎骞冲潎鍊笺傜悊瑙ｉ殢鏈哄彉閲忕殑鍒嗗竷鍒楀拰鏁板鏈熸湜鍏紡鏈夊姪浜庢垜浠洿濂藉湴鐞嗚В闅忔満鍙橀噺鐨勫垎甯冪壒寰佸拰骞冲潎鍙栧兼儏鍐碉紝骞朵笖鍦ㄧ粺璁″鍜屾鐜囪鐨勫簲鐢ㄤ腑鍏锋湁閲嶈鎰忎箟銆
绛旓細1.鍒嗗竷鍒锛圥robability Mass Function锛孭MF锛夋弿杩颁簡绂绘暎闅忔満鍙橀噺鐨勫彇鍊煎強鍏跺搴旂殑姒傜巼銆傚浜庣鏁ｉ殢鏈哄彉閲 X 锛屽叾鍒嗗竷鍒楅氬父琛ㄧず涓 鍏朵腑 xi 鏄彲鑳界殑鍙栧硷紝鑰 pi 鏄浉搴斿彇鍊肩殑姒傜巼銆傚垎甯冨垪鍖呭惈浜嗘墍鏈夊彲鑳藉彇鍊煎強鍏跺搴旂殑姒傜巼淇℃伅銆2. 鏁板鏈熸湜锛圗xpected Value锛夋槸闅忔満鍙橀噺鐨勫钩鍧囧硷紝琛ㄧず浜嗛殢鏈哄彉閲忓湪涓...
绛旓細鍒嗗竷鍒楁槸姒傜巼璁轰腑鐨勪竴涓噸瑕佹蹇碉紝鐢ㄤ簬鎻忚堪闅忔満鍙橀噺鍙栧悇涓彲鑳藉肩殑姒傜巼銆傚亣璁鹃殢鏈哄彉閲 X 鍙互鍙栫殑鍊兼湁 x1, x2, ..., xn锛屽垯鍒嗗竷鍒 P(X=xi) 琛ㄧず闅忔満鍙橀噺 X 鍙栧 xi 鐨勬鐜囥鏁板鏈熸湜鍏紡鏄敤浜庤绠楅殢鏈哄彉閲忔暟瀛︽湡鏈涚殑鍏紡锛屽叾瀹氫箟涓 E(X) = 危 (xi * P(X=xi))锛屽叾涓 危 琛ㄧず姹傚拰绗﹀彿...
