Ôn tập chương III

Home Lớp 7 Toán lớp 7 - Sách kết nối tri thức Ôn tập chương IIIBài tập nâng cao

{"common":{"save":0,"post_id":"1392","level":3,"total":10,"point":10,"point_extra":0},"segment":[{"id":"1031","post_id":"1392","mon_id":"0","chapter_id":"0","question":"L\u1ef1a ch\u1ecdn \u0111\u00e1p \u00e1n \u0111\u00fang nh\u1ea5t","options":{"time":24,"part":[{"title":"L\u1ef1a ch\u1ecdn \u0111\u00e1p \u00e1n \u0111\u00fang nh\u1ea5t","title_trans":"\u0110\u1ec1 chung cho hai c\u00e2u","temp":"multiple_choice","correct":[[4]],"list":[{"point":10,"ques":"Ng\u01b0\u1eddi ta \u0111\u1ebfm m\u1ed9t c\u00e1ch c\u1ea9n th\u1eadn s\u1ed1 c\u00e1nh hoa tr\u00ean $100$ b\u00f4ng hoa v\u00e0 ghi l\u1ea1i nh\u01b0 sau: <br\/> <table><tr><th>S\u1ed1 c\u00e1nh hoa $(x)$<\/th><th>T\u1ea7n s\u1ed1 $(n)$<\/th><\/tr><tr><td>$10-12$<\/td><td>5<\/td><\/tr><tr><td>$13-15$<\/td><td>22<\/td><\/tr><tr><td>$16-18$<\/td><td>48<\/td><\/tr><tr><td>$19-21$<\/td><td>18<\/td><\/tr><tr><td>$22-24$<\/td><td>7<\/td><\/tr><tr><td><\/td><td>$N=100$<\/td><\/tr><\/table> <br\/> C\u00e2u 1. <\/b> S\u1ed1 ph\u1ea7n tr\u0103m nh\u1eefng b\u00f4ng hoa quan s\u00e1t \u0111\u01b0\u1ee3c v\u1edbi s\u1ed1 c\u00e1nh hoa \u00edt h\u01a1n $19,$ ch\u00ednh x\u00e1c l\u00e0: <\/span>","select":["A. $48\\%$","B. $52\\%$","C. $72\\%$ ","D. $75\\%$"],"explain":"H\u01b0\u1edbng d\u1eabn:<\/span><br\/>T\u00ecm s\u1ed1 b\u00f4ng hoa quan s\u00e1t \u0111\u01b0\u1ee3c c\u00f3 s\u1ed1 c\u00e1nh \u00edt h\u01a1n $19$ <br\/> T\u00ednh t\u1ec9 s\u1ed1 ph\u1ea7n tr\u0103m gi\u1eefa s\u1ed1 hoa c\u00f3 s\u1ed1 c\u00e1nh \u00edt h\u01a1n $19$ v\u1edbi s\u1ed1 hoa quan s\u00e1t <br\/> B\u00e0i gi\u1ea3i:<\/span><br\/>S\u1ed1 b\u00f4ng hoa quan s\u00e1t \u0111\u01b0\u1ee3c c\u00f3 s\u1ed1 c\u00e1nh \u00edt h\u01a1n $19$ l\u00e0: <br\/> $5+22+48=75$ (b\u00f4ng hoa) <br\/> S\u1ed1 ph\u1ea7n tr\u0103m nh\u1eefng b\u00f4ng hoa quan s\u00e1t \u0111\u01b0\u1ee3c v\u1edbi s\u1ed1 c\u00e1nh hoa \u00edt h\u01a1n $19$ l\u00e0: <br\/> $\\dfrac{75}{100}\\cdot 100\\%=75\\%$ <br\/> V\u1eady \u0111\u00e1p \u00e1n l\u00e0 D.<\/span> <\/span>","column":4}]}]},"correct":"","level":"3","hint":"","answer":"","type":"json","extra_type":"","time":"0","user_id":"0","test":"0","date":"2019-09-30 09:22:54"},{"id":"1032","post_id":"1392","mon_id":"0","chapter_id":"0","question":"L\u1ef1a ch\u1ecdn \u0111\u00e1p \u00e1n \u0111\u00fang nh\u1ea5t","options":{"time":24,"part":[{"title":"L\u1ef1a ch\u1ecdn \u0111\u00e1p \u00e1n \u0111\u00fang nh\u1ea5t","title_trans":"\u0110\u1ec1 chung cho hai c\u00e2u","temp":"multiple_choice","correct":[[3]],"list":[{"point":10,"ques":"Ng\u01b0\u1eddi ta \u0111\u1ebfm m\u1ed9t c\u00e1ch c\u1ea9n th\u1eadn s\u1ed1 c\u00e1nh hoa tr\u00ean $100$ b\u00f4ng hoa v\u00e0 ghi l\u1ea1i nh\u01b0 sau: <br\/> <table><tr><th>S\u1ed1 c\u00e1nh hoa $(x)$<\/th><th>T\u1ea7n s\u1ed1 $(n)$<\/th><\/tr><tr><td>$10-12$<\/td><td>5<\/td><\/tr><tr><td>$13-15$<\/td><td>22<\/td><\/tr><tr><td>$16-18$<\/td><td>48<\/td><\/tr><tr><td>$19-21$<\/td><td>18<\/td><\/tr><tr><td>$22-24$<\/td><td>7<\/td><\/tr><tr><td><\/td><td>$N=100$<\/td><\/tr><\/table> <br\/> C\u00e2u 2. <\/b> Trung b\u00ecnh m\u1ed7i b\u00f4ng hoa c\u00f3 s\u1ed1 c\u00e1nh l\u00e0:<\/span>","select":["A. $15$","B. $16$","C. $17$ ","D. $18$"],"explain":"H\u01b0\u1edbng d\u1eabn:<\/span><br\/>T\u00ecm s\u1ed1 trung b\u00ecnh c\u1ed9ng c\u1ee7a d\u1ea5u hi\u1ec7u \u0111\u00f3 ch\u00ednh l\u00e0 s\u1ed1 c\u00e1nh trung b\u00ecnh c\u1ee7a m\u1ed7i b\u00f4ng hoa. <br\/> B\u00e0i gi\u1ea3i:<\/span><br\/>Ta c\u00f3 b\u1ea3ng sau: <br\/><table><tr><th>S\u1ed1 c\u00e1nh hoa $(x)$<\/th><th>Trung b\u00ecnh c\u1ed9ng c\u1ee7a kho\u1ea3ng<\/th><th>T\u1ea7n s\u1ed1 $(n)$<\/th><th>C\u00e1c t\u00edch<\/th><\/tr><tr><td>$10-12$<\/td><td>11<\/td><td>5<\/td><td>55<\/td><\/tr><tr><td>$13-15$<\/td><td>14<\/td><td>22<\/td><td>308<\/td><\/tr><tr><td>$16-18$<\/td><td>17<\/td><td>48<\/td><td>816<\/td><\/tr><tr><td>$19-21$<\/td><td>20<\/td><td>18<\/td><td>360<\/td><\/tr><tr><td>$22-24$<\/td><td>23<\/td><td>7<\/td><td>161<\/td><\/tr><tr><td><\/td><td><\/td><td>$N=100$<\/td><td>T\u1ed5ng: $1700$<\/td><\/tr><\/table> <br\/> Trung b\u00ecnh m\u1ed7i b\u00f4ng hoa c\u00f3 s\u1ed1 c\u00e1nh l\u00e0: <br\/> $\\overline{X}=\\dfrac{1700}{100}=17$ (c\u00e1nh) <br\/> V\u1eady \u0111\u00e1p \u00e1n l\u00e0 C.<\/span> <br\/> L\u01b0u \u00fd:<\/b> \u0110\u1ed1i v\u1edbi b\u1ea3ng m\u00e0 gi\u00e1 tr\u1ecb \u0111\u1ec3 \u1edf d\u1ea1ng kho\u1ea3ng th\u00ec ta t\u00ednh s\u1ed1 trung b\u00ecnh c\u1ed9ng c\u1ee7a d\u1ea5u hi\u1ec7u nh\u01b0 sau: <br\/> - T\u00ednh s\u1ed1 trung b\u00ecnh c\u1ed9ng c\u1ee7a t\u1eebng kho\u1ea3ng. S\u1ed1 \u0111\u00f3 ch\u00ednh l\u00e0 trung b\u00ecnh c\u1ed9ng c\u1ee7a gi\u00e1 tr\u1ecb l\u1edbn nh\u1ea5t v\u00e0 nh\u1ecf nh\u1ea5t c\u1ee7a kho\u1ea3ng. V\u00ed d\u1ee5 trung b\u00ecnh c\u1ed9ng c\u1ee7a kho\u1ea3ng $150-152$ l\u00e0 $151.$ <br\/> - Nh\u00e2n c\u00e1c s\u1ed1 trung b\u00ecnh v\u1eeba t\u00ecm \u0111\u01b0\u1ee3c v\u1edbi c\u00e1c t\u1ea7n s\u1ed1 t\u01b0\u01a1ng \u1ee9ng. <br\/> - T\u00ecm s\u1ed1 trung b\u00ecnh c\u1ed9ng theo c\u00f4ng th\u1ee9c \u0111\u00e3 h\u1ecdc.<\/span>","column":4}]}]},"correct":"","level":"3","hint":"","answer":"","type":"json","extra_type":"","time":"0","user_id":"0","test":"0","date":"2019-09-30 09:22:54"},{"id":"1033","post_id":"1392","mon_id":"0","chapter_id":"0","question":"\u0110i\u1ec1n k\u1ebft qu\u1ea3 \u0111\u00fang nh\u1ea5t v\u00e0o \u00f4 tr\u1ed1ng","options":{"time":24,"part":[{"title":"\u0110i\u1ec1n k\u1ebft qu\u1ea3 \u0111\u00fang nh\u1ea5t v\u00e0o \u00f4 tr\u1ed1ng","title_trans":"\u0110\u1ec1 chung cho hai c\u00e2u","temp":"fill_the_blank","correct":[[["5"],["6"]]],"list":[{"point":10,"width":40,"content":"","type_input":"","ques":" Cho b\u1ea3ng s\u1ed1 li\u1ec7u sau: <br\/> <table><tr><th>Gi\u00e1 tr\u1ecb $(x)$<\/th><th>T\u1ea7n s\u1ed1 $(n)$<\/th><\/tr><tr><td>1<\/td><td>2<\/td><\/tr><tr><td>2<\/td><td>$k$<\/td><\/tr><tr><td>3<\/td><td>4<\/td><\/tr><tr><td>4<\/td><td>8<\/td><\/tr><tr><td>5<\/td><td>5<\/td><\/tr><tr><td>6<\/td><td>$y$<\/td><\/tr><\/table> <br\/> Bi\u1ebft s\u1ed1 trung b\u00ecnh c\u1ed9ng c\u1ee7a d\u1ea5u hi\u1ec7u l\u00e0 $3,9$ <br\/> C\u00e2u 1.<\/b> Bi\u1ebft $N=30.$ T\u00ecm $k, y.$ <br\/> \u0110\u00e1p \u00e1n: <\/b> $k=\\FormInput[40][bl_elm_true basic_elm basic_blank basic_blank_part]{};y=\\FormInput[40][bl_elm_true basic_elm basic_blank basic_blank_part]{}$ <\/span>","explain":"H\u01b0\u1edbng d\u1eabn:<\/span><br\/>T\u00ecm m\u1ed1i li\u00ean h\u1ec7 gi\u1eefa $k$ v\u00e0 $y$ theo hai d\u1eef ki\u1ec7n: <br\/> + S\u1ed1 c\u00e1c gi\u00e1 tr\u1ecb c\u1ee7a d\u1ea5u hi\u1ec7u <br\/> + S\u1ed1 trung b\u00ecnh c\u1ed9ng c\u1ee7a d\u1ea5u hi\u1ec7u <br\/> T\u1eeb \u0111\u00f3 l\u1eadp lu\u1eadn \u0111\u1ec3 t\u00ecm gi\u00e1 tr\u1ecb c\u1ee7a $k$ v\u00e0 $y.$ <br\/> B\u00e0i gi\u1ea3i:<\/span><br\/>Theo b\u00e0i s\u1ed1 c\u00e1c gi\u00e1 tr\u1ecb $(N)$ l\u00e0 $30.$ <br\/> Khi \u0111\u00f3: <br\/> $\\begin{align} & N=30 \\\\ & \\Leftrightarrow 2+k+4+8+5+y=30 \\\\ & \\Leftrightarrow 19+k+y=30 \\\\ & \\Leftrightarrow k+y=30-19 \\\\ & \\Leftrightarrow k+y=11\\,\\,\\,\\,\\,\\,\\,\\,\\,\\,\\,\\left( 1 \\right) \\\\ \\end{align}$ <br\/> L\u1ea1i c\u00f3, s\u1ed1 trung b\u00ecnh c\u1ed9ng l\u00e0 $3,9$ n\u00ean: <br\/> $\\begin{align} & \\overline{X}=3,9 \\\\ & \\Leftrightarrow \\dfrac{1.2+2.k+3.4+4.8+5.5+6.y}{30}=3,9 \\\\ & \\Leftrightarrow \\dfrac{71+2k+6y}{30}=3,9 \\\\ & \\Leftrightarrow 71+2k+6y=117 \\\\ & \\Leftrightarrow 2k+6y=46 \\\\ & \\Leftrightarrow k+3y=23\\,\\,\\,\\,\\,\\,\\,\\,\\left( 2 \\right) \\\\ \\end{align}$ <br\/> T\u1eeb (1) v\u00e0 (2) ta c\u00f3: <br\/> $\\begin{align} & k+3y=23 \\\\ & \\Leftrightarrow \\left( k+y \\right)+2y=23 \\\\ & \\Leftrightarrow 11+2y=23 \\\\ & \\Leftrightarrow 2y=12 \\\\ & \\Leftrightarrow y=6 \\\\ & \\Rightarrow k=11-6=5 \\\\ \\end{align}$ <br\/> V\u1eady c\u00e1c s\u1ed1 c\u1ea7n \u0111i\u1ec1n v\u00e0o c\u00e1c \u00f4 tr\u1ed1ng l\u1ea7n l\u01b0\u1ee3t l\u00e0 $5;6$<\/span><\/span>"}]}]},"correct":"","level":"3","hint":"","answer":"","type":"json","extra_type":"","time":"0","user_id":"0","test":"0","date":"2019-09-30 09:22:54"}]}