Hai bài toán về phân số - Bài tập nâng cao

Home Lớp 6 Toán lớp 6 - Sách kết nối tri thức Bài 27: Hai bài toán về phân sốBài tập nâng cao

{"common":{"save":0,"post_id":"4553","level":3,"total":10,"point":10,"point_extra":0},"segment":[{"id":"6469","post_id":"4553","mon_id":"1158113","chapter_id":"1158119","question":"M\u1ed9t h\u1ed9p bánh có 45 chi\u1ebfc. Các chi\u1ebfc bánh trong h\u1ed9p gi\u1ed1ng nhau nh\u01b0ng \u0111\u01b0\u1ee3c b\u1ecdc b\u1eb1ng hai lo\u1ea1i gi\u1ea5y có màu khác nhau: tr\u1eafng và \u0111en. S\u1ed1 bánh b\u1ecdc trong gi\u1ea5y tr\u1eafng chi\u1ebfm  4<\/span>9<\/span><\/span>  s\u1ed1 bánh trong h\u1ed9p. Di\u1ec7n tích m\u1ed7i t\u1edd gi\u1ea5y b\u1ecdc m\u1ed9t chi\u1ebfc bánh \u0111\u1ec1u b\u1eb1ng 120 $cm^{2}$<\/span>. Tính di\u1ec7n tích m\u1ed7i lo\u1ea1i gi\u1ea5y (tr\u1eafng và \u0111en) c\u1ea7n dùng \u0111\u1ec3 b\u1ecdc bánh trong h\u1ed9p bánh \u0111ó.<\/p><div class=\"lt123_imgs\"><img class=\"img_dd tiny\" src=\"\/data\/library\/do-an\/hop-banh2.png\" \/><\/div>","options":["2400 $cm^{2}$<\/span> gi\u1ea5y tr\u1eafng và 3000 $cm^{2}$<\/span> gi\u1ea5y \u0111en","3000 $cm^{2}$<\/span> gi\u1ea5y tr\u1eafng và 2400 $cm^{2}$<\/span> gi\u1ea5y \u0111en"],"correct":"1","level":"3","hint":"Dùng quy t\u1eafc: 'Mu\u1ed1n tìm $\\dfrac{m}{n}$<\/span> c\u1ee7a m\u1ed9t s\u1ed1  $a$<\/span>  cho tr\u01b0\u1edbc ta tính   $a.\\dfrac{m}{n}$<\/span> .' \u0111\u1ec3 tính s\u1ed1 bánh m\u1ed7i lo\u1ea1i r\u1ed3i tính di\u1ec7n tích m\u1ed7i lo\u1ea1i gi\u1ea5y.<\/p>","answer":"S\u1ed1 chi\u1ebfc bánh b\u1ecdc gi\u1ea5y màu tr\u1eafng là     $\\dfrac{4}{9}.45=4.5=$<\/span> 20 (chi\u1ebfc).<\/p>S\u1ed1 chi\u1ebfc bánh b\u1ecdc gi\u1ea5y màu \u0111en  là      45 - 20 = 25  (chi\u1ebfc).<\/p>Di\u1ec7n tích gi\u1ea5y gói màu tr\u1eafng<\/span> là       20 . 120 = 2400  ($cm^{2}$<\/span>)<\/span><\/p>Di\u1ec7n tích gi\u1ea5y gói màu \u0111en<\/span> là          25 . 120 = 3000 ($cm^{2}$<\/span>)<\/span><\/p>\u0110áp án \u0111úng là  2400 $cm^{2}$<\/span> gi\u1ea5y tr\u1eafng và 3000 $cm^{2}$<\/span> gi\u1ea5y \u0111en<\/span><\/strong><\/p>","type":"choose","extra_type":"classic","time":"0","user_id":"131","test":"1","date":"2021-08-25 12:51:09","option_type":"math","len":0},{"id":"6472","post_id":"4553","mon_id":"1158113","chapter_id":"1158119","question":"M\u1ed9t xe ô tô và m\u1ed9t xe máy kh\u1edfi hành cùng lúc theo hai h\u01b0\u1edbng ng\u01b0\u1ee3c nhau: ô tô \u0111i t\u1eeb A \u0111\u1ebfn B, xe máy \u0111i t\u1eeb B \u0111\u1ebfn A. Sau 5 gi\u1edd hai xe ch\u01b0a g\u1eb7p nhau và còn cách nhau 120 km. Bi\u1ebft r\u1eb1ng \u0111\u1ec3 \u0111i h\u1ebft quãng \u0111\u01b0\u1eddng AB, ô tô ph\u1ea3i \u0111i trong 12 gi\u1edd và xe máy ph\u1ea3i \u0111i trong 15 gi\u1edd liên t\u1ee5c v\u1edbi v\u1eadn t\u1ed1c không \u0111\u1ed5i. Tính chi\u1ec1u dài quãng \u0111\u01b0\u1eddng AB.<\/p><div class=\"_rbieudo2\">Quãng \u0111\u01b0\u1eddng AB dài<\/strong> <input class=\"tim_x input_number\" tpl=\"dien_so\" type=\"text\"\/>  km<\/strong>.<\/div>","options":"","correct":["[\"480\"]"],"level":"3","hint":"","answer":"M\u1ed7i gi\u1edd ô tô \u0111i \u0111\u01b0\u1ee3c       1<\/span>12<\/span><\/span>  quãng \u0111\u01b0\u1eddng.<\/p>M\u1ed7i gi\u1edd xe máy \u0111i \u0111\u01b0\u1ee3c  1<\/span>15<\/span><\/span>  quãng \u0111\u01b0\u1eddng.<\/p>M\u1ed7i gi\u1edd hai xe cùng \u0111i \u0111\u01b0\u1ee3c   1<\/span>12<\/span><\/span>+<\/span>1<\/span>15<\/span><\/span>= <\/span>5<\/span>60<\/span><\/span>+<\/span>4<\/span>60<\/span><\/span>= <\/span>9<\/span>60<\/span><\/span>= <\/span>3<\/span>20<\/span><\/span> (quãng \u0111\u01b0\u1eddng).<\/p>Sau 5 gi\u1edd hai xe cùng \u0111i \u0111\u01b0\u1ee3c 5<\/span>.<\/span>3<\/span>20<\/span><\/span>= <\/span>3<\/span>4<\/span><\/span> (quãng \u0111\u01b0\u1eddng)<\/p>Sau 5 gi\u1edd hai xe còn cách nhau 1  -  3<\/span>4<\/span><\/span>   =   1<\/span>4<\/span><\/span>   (quãng \u0111\u01b0\u1eddng), \u1ee9ng v\u1edbi 120 km.<\/p>V\u1eady quãng \u0111\u01b0\u1eddng AB dài  120 :  1<\/span>4<\/span><\/span>   =120 . 4 = 480 (km)<\/span><\/strong><\/p>S\u1ed1 c\u1ea7n \u0111i\u1ec1n là  480<\/strong><\/span>.<\/p>","type":"blank","extra_type":"","time":"0","user_id":"131","test":"1","date":"2021-08-25 13:13:50"},{"id":"6491","post_id":"4553","mon_id":"1158113","chapter_id":"1158119","question":"M\u1ed9t tr\u01b0\u1eddng THCS có 420 h\u1ecdc sinh g\u1ed3m h\u1ecdc sinh gi\u1ecfi, khá và trung bình. K\u1ebft thúc h\u1ecdc kì 1, s\u1ed1 h\u1ecdc sinh gi\u1ecfi b\u1eb1ng1<\/span>7<\/span><\/span>  s\u1ed1 h\u1ecdc sinh toàn tr\u01b0\u1eddng, s\u1ed1 h\u1ecdc sinh h\u1ecdc sinh khá b\u1eb1ng4<\/span>3<\/span><\/span>  t\u1ed5ng s\u1ed1 h\u1ecdc sinh gi\u1ecfi và h\u1ecdc sinh trung bình. Tính s\u1ed1 h\u1ecdc sinh m\u1ed7i lo\u1ea1i.<\/p>","options":[["Gi\u1ecfi","Khá ","Trung bình"],["120 h\u1ecdc sinh","60 h\u1ecdc sinh","240 h\u1ecdc sinh"],["60 h\u1ecdc sinh","240 h\u1ecdc sinh","120 h\u1ecdc sinh"]],"correct":[2,0,1],"level":"3","hint":"","answer":"S\u1ed1 h\u1ecdc sinh gi\u1ecfi<\/span> là:   $\\dfrac{1}{7}.420=$<\/span>  60 (h\u1ecdc sinh)<\/span><\/p>S\u1ed1 h\u1ecdc sinh khá b\u1eb1ng  $\\dfrac{4}{3}$<\/span> t\u1ed5ng s\u1ed1 h\u1ecdc sinh gi\u1ecfi và h\u1ecdc sinh trung bình nên s\u1ed1 h\u1ecdc sinh khá b\u1eb1ng <\/p>$\\dfrac{4}{4+3}=\\dfrac{4}{7}$<\/span> s\u1ed1 h\u1ecdc sinh toàn tr\u01b0\u1eddng<\/p>Suy ra s\u1ed1 h\u1ecdc sinh khá<\/span> là  $\\dfrac{4}{7}.420=$<\/span>  240 (h\u1ecdc sinh)<\/span><\/p>S\u1ed1 h\u1ecdc sinh trung bình<\/span> là   420 - 60 - 240 = 120 (h\u1ecdc sinh)<\/span><\/p>V\u1eady \u0111áp án c\u1ea7n n\u1ed1i là<\/p>Gi\u1ecfi:  60 h\u1ecdc sinh<\/span><\/p>Khá:  240 h\u1ecdc sinh<\/span><\/p>Trung bình:  120 h\u1ecdc sinh<\/span><\/p>","type":"matching","extra_type":"mat_txt","time":"0","user_id":"131","test":"3","date":"2021-08-25 15:19:08"}]}