DmivaHpc so 5 2 43 Cac ufng dung cua phan phd''''i chuan ThS TRAN MINH DIEP TrUdng Dpi hpc Chfnh In PliSn phoi chuan (Normal distribution) la phan phoi lien tyc dugc ap dyng rong rai trong thuc te, Trong[.]
43 DmivaHpc so Cac ufng dung cua phan phd'i chuan ThS TRAN MINH DIEP TrUdng Dpi hpc Chfnh In P liSn phoi chuan (Normal distribution) la phan phoi lien tyc dugc ap dyng rong rai thuc te, Trong nhieu ITnh vyc cua Idioa hoc va dai song ta deu gap cac bien ngau nhien co phan plioi chuan Nhieu tac gia da trinh bay kha kyCac npi dung lien quan din phan ph6i chuan, bai vilt trinh bay cac img dung c6 tinh thyc tien ciia phan phoi chuan hay gap cuoc song thudng Bien ngdu nhien lien t\ic X nhgn gid tri khoang ('-GO;+COJ goi la phan phoi theo quy luat chuan vdi cac tham so fiva d^, neu ham mat xac sudt cua no co dang: ' (-^-f'f /w= V27 -._ Ba ieng dung quan trpng cua phan phoi chuan (1) Nhieu qua trinh ngau nhien xay mot each tu nhien co xu hudng tuan theo mot quy luat phan phoi xap xi Chuan Chang han: y te, cac dac tinh sinh trac hoc cua nguai khoe manh (can nang, chieu cao, trj so mach, huyet ap, duo'ng mau, s6 lupng h6ng cau); nong nghiep, nang xuat cua mot loai cay tai cac thua ru^ng khac nhau; kinh doanh, nhu cau ve cac lopi hang hoa khac nhau; giao dye, diem thi cac mon hoc ciia cac hoc sinh; , (2) Mot phan phoi dua tren nhieu quan sat(chang han phan phoi Nhj thuc) se tiem can phan phoi ChuSn s6 quan sat (n) dii 16n («> 30 thuong dugc coi la dii lan) phuong sai o-^ thi Xi+ X2 cung tudn theo quy lugt phdn phoi Chudn vai ky vgng fi\ + fi2 vd phuong sai - Cac phircng phap tinh Bdi toan 1: Su dung phan ph6i Chudn tinh cac xac sudt De tinh cac xac suat lien quan den mot phan phoi chuan ta sii dung phuong phap sau day: Budc 1: Dua yeu cau bai toan ve dang: P(X < c) Budc 2: Chuan hoa ve bien ngau nhierj Z (phan phoi chuan vai trung binh bang va lech chuan bang 1) theo cong thuc X-Ll Z= Budc 3: Tra bang phan phoi chuan de tinb xac suat p(zz)=l- P(2