Tr\u01b0\u1edbc khi ti\u1ebfn h\u00e0nh c\u00e1c tr\u1eadn \u0111\u1ea5u b\u00f3ng \u0111\u00e1, ng\u01b0\u1eddi tr\u1ecdng t\u00e0i th\u01b0\u1eddng n\u00e9m (tung) \u0111\u1ed3ng xu \u0111\u1ec3 xem s\u1ef1 xu\u1ea5t hi\u1ec7n m\u1eb7t s\u1ea5p hay ng\u1eeda l\u00ean tr\u00ean m\u00e0 quy\u1ebft \u0111\u1ecbnh \u0111\u1ed9i giao b\u00f3ng tr\u01b0\u1edbc.<\/p>\n\n\n\n
V\u1edbi m\u1ed9t \u0111\u1ed9i \u0111i thi \u0111\u1ea5u b\u00f3ng \u0111\u00e1 th\u00ec vi\u1ec7c giao b\u00f3ng tr\u01b0\u1edbc hay sau kh\u00f4ng c\u00f3 g\u00ec quan tr\u1ecdng. Tuy nhi\u00ean n\u00ean ch\u00fa \u00fd vi\u1ec7c khi n\u00e9m \u0111\u1ed3ng xu nhi\u1ec1u l\u1ea7n ta s\u1ebd th\u1ea5y s\u1ed1 l\u1ea7n xu\u1ea5t hi\u1ec7n m\u1eb7t tr\u00e1i v\u00e0 m\u1eb7t ph\u1ea3i nh\u01b0 nhau. V\u00ec sao v\u1eady?<\/p>\n\n\n\n
\u0110\u00f3 ch\u00ednh l\u00e0 do t\u00e1c \u0111\u1ed9ng c\u1ee7a quy lu\u1eadt to\u00e1n th\u1ed1ng k\u00ea. Ta th\u1eed n\u00e9m \u0111\u1ed3ng xu m\u1ed9t l\u1ea7n, tr\u01b0\u1edbc khi n\u00e9m \u0111\u1ed3ng xu ta ch\u01b0a th\u1ec3 n\u00f3i g\u00ec v\u1ec1 k\u1ebft qu\u1ea3 c\u1ee7a ph\u00e9p th\u1eed (m\u1eb7t tr\u00e1i hay m\u1eb7t ph\u1ea3i \u1edf ph\u00eda tr\u00ean). Nh\u01b0ng n\u1ebfu ta n\u00e9m \u0111\u1ed3ng xu nhi\u1ec1u l\u1ea7n th\u00ec l\u1ea1i c\u00f3 th\u1ec3 ti\u00ean \u0111o\u00e1n k\u1ebft qu\u1ea3 c\u1ee7a c\u00e1c ph\u00e9p n\u00e9m th\u1eed (g\u1ecdi t\u1eaft l\u00e0 ph\u00e9p th\u1eed).<\/p>\n\n\n\n
Gi\u1ea3 s\u1eed trong ph\u00e9p th\u1eed tr\u00ean \u0111\u00e2y, ta g\u1ecdi s\u1ef1 ki\u1ec7n xu\u1ea5t hi\u1ec7n m\u1eb7t ng\u1eeda c\u1ee7a \u0111\u1ed3ng xu l\u00ean tr\u00ean, ta g\u1ecdi l\u00e0 s\u1ef1 ki\u1ec7n A, c\u00f2n vi\u1ec7c xu\u1ea5t hi\u1ec7n m\u1eb7t s\u1ea5p l\u00ean tr\u00ean l\u00e0 s\u1ef1 ki\u1ec7n B. Kh\u1ea3 n\u0103ng xu\u1ea5t hi\u1ec7n s\u1ef1 ki\u1ec7n A ho\u1eb7c s\u1ef1 ki\u1ec7n B khi n\u00e9m \u0111\u1ed3ng xu \u0111\u01b0\u1ee3c g\u1ecdi l\u00e0 x\u00e1c su\u1ea5t P(A) v\u00e0 P(B). Vi\u1ec7c l\u1eb7p l\u1ea1i nhi\u1ec1u l\u1ea7n ph\u00e9p th\u1eed th\u00ec vi\u1ec7c xu\u1ea5t hi\u1ec7n s\u1ef1 ki\u1ec7n A hay B c\u00f3 t\u00ednh quy lu\u1eadt g\u1ecdi l\u00e0 t\u00ednh th\u1ed1ng k\u00ea. Gi\u1ea3 s\u1eed sau nhi\u1ec1u l\u1ea7n n\u00e9m \u0111\u1ed3ng xu v\u00ed d\u1ee5 n l\u1ea7n, s\u1ef1 xu\u1ea5t hi\u1ec7n s\u1ef1 ki\u1ec7n A c\u00f3 nA l\u1ea7n, c\u00f2n xu\u1ea5t hi\u1ec7n s\u1ef1 ki\u1ec7n B l\u00e0 nB l\u1ea7n, nA l\u00e0 t\u1ea7n s\u1ed1 xu\u1ea5t hi\u1ec7n s\u1ef1 ki\u1ec7n A, nB l\u00e0 t\u1ea7n s\u1ed1 xu\u1ea5t hi\u1ec7n s\u1ef1 ki\u1ec7n B, ta g\u1ecdi fn(A) = nA\/n l\u00e0 t\u1ea7n su\u1ea5t xu\u1ea5t hi\u1ec7n s\u1ef1 ki\u1ec7n A. N\u1ebfu fn(A) c\u00e0ng l\u1edbn th\u00ec s\u1ef1 xu\u1ea5t hi\u1ec7n s\u1ef1 ki\u1ec7n A c\u00e0ng d\u00e0y v\u00e0 trong m\u1ed9t ph\u00e9p th\u1eed kh\u1ea3 n\u0103ng xu\u1ea5t hi\u1ec7n s\u1ef1 ki\u1ec7n A c\u00e0ng l\u1edbn. Khi th\u1ef1c hi\u1ec7n ph\u00e9p th\u1eed nhi\u1ec1u l\u1ea7n th\u00ec t\u1ea7n su\u1ea5t fn(A) c\u00e0ng d\u1ea7n ti\u1ebfn \u0111\u1ebfn x\u00e1c su\u1ea5t P(A) c\u1ee7a s\u1ef1 ki\u1ec7n A.<\/p>\n\n\n\n
Qua c\u00e1c t\u00ednh to\u00e1n c\u1ee5 th\u1ec3 ta c\u00f3 th\u1ec3 nh\u1eadn r\u00f5 \u0111\u01b0\u1ee3c t\u00ednh quy lu\u1eadt n\u00e0y. Gi\u1ea3 s\u1eed c\u00e1ch n\u00e9m \u0111\u1ed3ng xu l\u00e0 th\u1ef1c hi\u1ec7n nh\u01b0 nhau trong c\u00e1c l\u1ea7n n\u00e9m, s\u1ef1 xu\u1ea5t hi\u1ec7n s\u1ef1 ki\u1ec7n A hay B trong m\u1ed7i l\u1ea7n n\u00e9m l\u00e0 nh\u01b0 nhau (\u0111\u1ed3ng kh\u1ea3 n\u0103ng) n\u00ean P(A) = P(B) = 0,5, ho\u1eb7c c\u00f3 th\u1ec3 vi\u1ebft P(nA = 1) = P(nA = 0) = 0,5. N\u1ebfu th\u1ef1c hi\u1ec7n nhi\u1ec1u l\u1ea7n ph\u00e9p th\u1eed c\u00f3 th\u1ec3 xu\u1ea5t hi\u1ec7n b\u1ed1n lo\u1ea1i k\u1ebft qu\u1ea3: (A,A) (A,B) (B,A) (B,B). d\u1ec5 d\u00e0ng t\u00ecm th\u1ea5y<\/p>\n\n\n\n
P(nA = 2) = 0,25<\/p>\n\n\n\n
P(nA = 1) = 0,5<\/p>\n\n\n\n
P(nA = 0) = 0,25<\/p>\n\n\n\n
V\u00ed d\u1ee5 sau 10.000 l\u1ea7n th\u1ef1c hi\u1ec7n ph\u00e9p th\u1eed ng\u01b0\u1eddi ta ghi l\u1ea1i \u0111\u01b0\u1ee3c s\u1ef1 ki\u1ec7n A xu\u1ea5t hi\u1ec7n 4900 – 5100 v\u00e0 4800 – 5200<\/p>\n\n\n\n
V\u00e0 x\u00e1c su\u1ea5t c\u1ee7a s\u1ef1 ki\u1ec7n P (4900 \u2264 nA \u2264 5100) \u2248 84,26%<\/p>\n\n\n\n
P(4800 \u2264 nA \u2264 5200) \u2248 99,54%. hay x\u00e1c su\u1ea5t \u0111\u1ec3<\/p>\n\n\n\n
P(0,49 \u2264 fn(A) \u2264 0,51\u2248 84,26%<\/p>\n\n\n\n
P(0,48 \u2264 fn(A) \u2264 0,52\u2248 99,54%<\/p>\n\n\n\n
\u0110\u00e3 c\u00f3 kh\u00e1 nhi\u1ec1u ng\u01b0\u1eddi th\u1ef1c hi\u1ec7n lo\u1ea1i ph\u00e9p th\u1eed k\u1ec3 tr\u00ean.<\/p>\n\n\n\n
T\u1eeb kho\u00e1: X\u00e1c xu\u1ea5t; Quy lu\u1eadt th\u1ed1ng k\u00ea; T\u1ea7n s\u1ed1; T\u1ea7n su\u1ea5t.<\/p>\n\n\n\n
<\/p>\n\n\n\n\n\n\n","protected":false},"excerpt":{"rendered":"
Tr\u01b0\u1edbc khi ti\u1ebfn h\u00e0nh c\u00e1c tr\u1eadn \u0111\u1ea5u b\u00f3ng \u0111\u00e1, ng\u01b0\u1eddi tr\u1ecdng t\u00e0i th\u01b0\u1eddng n\u00e9m (tung) \u0111\u1ed3ng xu \u0111\u1ec3 xem s\u1ef1 xu\u1ea5t hi\u1ec7n m\u1eb7t s\u1ea5p hay ng\u1eeda l\u00ean tr\u00ean m\u00e0 quy\u1ebft \u0111\u1ecbnh \u0111\u1ed9i giao b\u00f3ng tr\u01b0\u1edbc. V\u1edbi m\u1ed9t \u0111\u1ed9i \u0111i thi \u0111\u1ea5u b\u00f3ng \u0111\u00e1 th\u00ec vi\u1ec7c giao b\u00f3ng tr\u01b0\u1edbc hay sau kh\u00f4ng c\u00f3 g\u00ec quan tr\u1ecdng. […]<\/p>\n","protected":false},"author":1,"featured_media":0,"comment_status":"closed","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"footnotes":"","_disable_autopaging":false},"categories":[15,9],"tags":[],"class_list":["post-7690","post","type-post","status-publish","format-standard","hentry","category-hoi-dap-khoa-hoc","category-toan-hoc"],"_links":{"self":[{"href":"https:\/\/www.vietlearn.org\/kien-thuc\/wp-json\/wp\/v2\/posts\/7690","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/www.vietlearn.org\/kien-thuc\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/www.vietlearn.org\/kien-thuc\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/www.vietlearn.org\/kien-thuc\/wp-json\/wp\/v2\/users\/1"}],"replies":[{"embeddable":true,"href":"https:\/\/www.vietlearn.org\/kien-thuc\/wp-json\/wp\/v2\/comments?post=7690"}],"version-history":[{"count":0,"href":"https:\/\/www.vietlearn.org\/kien-thuc\/wp-json\/wp\/v2\/posts\/7690\/revisions"}],"wp:attachment":[{"href":"https:\/\/www.vietlearn.org\/kien-thuc\/wp-json\/wp\/v2\/media?parent=7690"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/www.vietlearn.org\/kien-thuc\/wp-json\/wp\/v2\/categories?post=7690"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/www.vietlearn.org\/kien-thuc\/wp-json\/wp\/v2\/tags?post=7690"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}