Các số đặc trưng đo xu thế trung tâm

Home Lớp 10 Toán lớp 10 - Sách Kết nối tri thức Bài 13. Các số đặc trưng đo xu thế trung tâmBài tập cơ bản

{"common":{"save":0,"post_id":"6444","level":1,"total":10,"point":10,"point_extra":0},"segment":[{"id":"6590","mon_id":"1158767","chapter_id":"1158885","post_id":"6444","question":"B\u1ea3ng sau cho bi\u1ebft th\u1eddi gian ch\u1ea1y c\u1ef1 li 100m c\u1ee7a các b\u1ea1n trong l\u1edbp (\u0111\u01a1n v\u1ecb giây):<\/p><svg height=\"95\" width=\"400\"> <g><title><\/title><rect fill=\"#fff\" height=\"97\" id=\"canvas_background\" width=\"402\" x=\"-1\" y=\"-1\"><\/rect> <g display=\"none\" id=\"canvasGrid\"> <rect fill=\"url(#gridpattern)\" height=\"100%\" id=\"svg_25\" stroke-width=\"0\" width=\"100%\" x=\"0\" y=\"0\"><\/rect> <\/g> <\/g> <g><title><\/title><g id=\"svg_29\" stroke=\"null\"> <rect fill=\"#56ffff\" height=\"44.5\" id=\"svg_1\" stroke=\"#000\" stroke-width=\"1.5\" width=\"101.50156\" x=\"2.01251\" y=\"4.23751\"><\/rect> <rect fill=\"#56ffff\" height=\"44.5\" id=\"svg_2\" stroke=\"#000\" stroke-width=\"1.5\" width=\"101.50156\" x=\"2.01251\" y=\"48.73751\"><\/rect> <text fill=\"#000000\" font-family=\"Helvetica, Arial, sans-serif\" font-size=\"17\" id=\"svg_3\" stroke=\"#000\" stroke-opacity=\"null\" stroke-width=\"0\" text-anchor=\"start\" transform=\"matrix(1.1183364449476818,0,0,1.390625,-1.2940124828400708,-7.124025374650955) \" x=\"8.19479\" xml:space=\"preserve\" y=\"30.17009\">Th\u1eddi gian<\/text> <text fill=\"#000000\" font-family=\"Helvetica, Arial, sans-serif\" font-size=\"17\" id=\"svg_4\" stroke=\"#000\" stroke-opacity=\"null\" stroke-width=\"0\" text-anchor=\"start\" transform=\"matrix(1.2229102928963584,0,0,1.390625,-1.894436357811344,-7.124025374650955) \" x=\"7.19479\" xml:space=\"preserve\" y=\"62.17009\">S\u1ed1 b\u1ea1n<\/text> <rect fill=\"#ffffff\" height=\"44.5\" id=\"svg_5\" stroke=\"#000\" stroke-width=\"1.5\" width=\"58.69969\" x=\"103.51407\" y=\"4.23751\"><\/rect> <rect fill=\"#ffffff\" height=\"44.5\" id=\"svg_6\" stroke=\"#000\" stroke-width=\"1.5\" width=\"58.69969\" x=\"103.51407\" y=\"48.73751\"><\/rect> <text fill=\"#000000\" font-family=\"Helvetica, Arial, sans-serif\" font-size=\"17\" id=\"svg_7\" stroke=\"#000\" stroke-opacity=\"null\" stroke-width=\"0\" text-anchor=\"start\" transform=\"matrix(1.2229102928963584,0,0,1.390625,-1.894436357811344,-7.124025374650955) \" x=\"99.19479\" xml:space=\"preserve\" y=\"30.17009\">12<\/text> <text fill=\"#000000\" font-family=\"Helvetica, Arial, sans-serif\" font-size=\"17\" id=\"svg_8\" stroke=\"#000\" stroke-opacity=\"null\" stroke-width=\"0\" text-anchor=\"start\" transform=\"matrix(1.2229102928963584,0,0,1.390625,-1.894436357811344,-7.124025374650955) \" x=\"106.19479\" xml:space=\"preserve\" y=\"62.17009\">5<\/text> <rect fill=\"#ffffff\" height=\"44.5\" id=\"svg_9\" stroke=\"#000\" stroke-width=\"1.5\" width=\"58.69969\" x=\"162.21376\" y=\"4.23751\"><\/rect> <rect fill=\"#ffffff\" height=\"44.5\" id=\"svg_10\" stroke=\"#000\" stroke-width=\"1.5\" width=\"58.69969\" x=\"162.21376\" y=\"48.73751\"><\/rect> <text fill=\"#000000\" font-family=\"Helvetica, Arial, sans-serif\" font-size=\"17\" id=\"svg_11\" stroke=\"#000\" stroke-opacity=\"null\" stroke-width=\"0\" text-anchor=\"start\" transform=\"matrix(1.2229102928963584,0,0,1.390625,-1.894436357811344,-7.124025374650955) \" x=\"147.19479\" xml:space=\"preserve\" y=\"30.17009\">13<\/text> <text fill=\"#000000\" font-family=\"Helvetica, Arial, sans-serif\" font-size=\"17\" id=\"svg_12\" stroke=\"#000\" stroke-opacity=\"null\" stroke-width=\"0\" text-anchor=\"start\" transform=\"matrix(1.2229102928963584,0,0,1.390625,-1.894436357811344,-7.124025374650955) \" x=\"154.19479\" xml:space=\"preserve\" y=\"62.17009\">7<\/text> <rect fill=\"#ffffff\" height=\"44.5\" id=\"svg_13\" stroke=\"#000\" stroke-width=\"1.5\" width=\"58.69969\" x=\"220.91345\" y=\"4.23751\"><\/rect> <rect fill=\"#ffffff\" height=\"44.5\" id=\"svg_14\" stroke=\"#000\" stroke-width=\"1.5\" width=\"58.69969\" x=\"220.91345\" y=\"48.73751\"><\/rect> <text fill=\"#000000\" font-family=\"Helvetica, Arial, sans-serif\" font-size=\"17\" id=\"svg_15\" stroke=\"#000\" stroke-opacity=\"null\" stroke-width=\"0\" text-anchor=\"start\" transform=\"matrix(1.2229102928963584,0,0,1.390625,-1.894436357811344,-7.124025374650955) \" x=\"195.19479\" xml:space=\"preserve\" y=\"30.17009\">14<\/text> <text fill=\"#000000\" font-family=\"Helvetica, Arial, sans-serif\" font-size=\"17\" id=\"svg_16\" stroke=\"#000\" stroke-opacity=\"null\" stroke-width=\"0\" text-anchor=\"start\" transform=\"matrix(1.2229102928963584,0,0,1.390625,-1.894436357811344,-7.124025374650955) \" x=\"195.19479\" xml:space=\"preserve\" y=\"62.17009\">10<\/text> <rect fill=\"#ffffff\" height=\"44.5\" id=\"svg_17\" stroke=\"#000\" stroke-width=\"1.5\" width=\"58.69969\" x=\"279.61315\" y=\"4.23751\"><\/rect> <rect fill=\"#ffffff\" height=\"44.5\" id=\"svg_18\" stroke=\"#000\" stroke-width=\"1.5\" width=\"58.69969\" x=\"279.61315\" y=\"48.73751\"><\/rect> <text fill=\"#000000\" font-family=\"Helvetica, Arial, sans-serif\" font-size=\"17\" id=\"svg_19\" stroke=\"#000\" stroke-opacity=\"null\" stroke-width=\"0\" text-anchor=\"start\" transform=\"matrix(1.2229102928963584,0,0,1.390625,-1.894436357811344,-7.124025374650955) \" x=\"243.19479\" xml:space=\"preserve\" y=\"30.17009\">15<\/text> <text fill=\"#000000\" font-family=\"Helvetica, Arial, sans-serif\" font-size=\"17\" id=\"svg_20\" stroke=\"#000\" stroke-opacity=\"null\" stroke-width=\"0\" text-anchor=\"start\" transform=\"matrix(1.2229102928963584,0,0,1.390625,-1.894436357811344,-7.124025374650955) \" x=\"250.19479\" xml:space=\"preserve\" y=\"62.17009\">8<\/text> <rect fill=\"#ffffff\" height=\"44.5\" id=\"svg_21\" stroke=\"#000\" stroke-width=\"1.5\" width=\"58.69969\" x=\"338.31284\" y=\"4.23751\"><\/rect> <rect fill=\"#ffffff\" height=\"44.5\" id=\"svg_22\" stroke=\"#000\" stroke-width=\"1.5\" width=\"58.69969\" x=\"338.31284\" y=\"48.73751\"><\/rect> <text fill=\"#000000\" font-family=\"Helvetica, Arial, sans-serif\" font-size=\"17\" id=\"svg_23\" stroke=\"#000\" stroke-opacity=\"null\" stroke-width=\"0\" text-anchor=\"start\" transform=\"matrix(1.2229102928963584,0,0,1.390625,-1.894436357811344,-7.124025374650955) \" x=\"291.19479\" xml:space=\"preserve\" y=\"30.17009\">16<\/text> <text fill=\"#000000\" font-family=\"Helvetica, Arial, sans-serif\" font-size=\"17\" id=\"svg_24\" stroke=\"#000\" stroke-opacity=\"null\" stroke-width=\"0\" text-anchor=\"start\" transform=\"matrix(1.2229102928963584,0,0,1.390625,-1.894436357811344,-7.124025374650955) \" x=\"298.19479\" xml:space=\"preserve\" y=\"62.17009\">6<\/text> <\/g> <\/g> <\/svg><\/span><\/p>Hãy tính th\u1eddi gian ch\u1ea1y trung bình c\u1ef1 li 100m c\u1ee7a các b\u1ea1n trong l\u1edbp.<\/p>","options":["A. <\/strong>14,08","B.<\/strong> 13,08","C.<\/strong> 15,08 ","D.<\/strong> 16,08"],"correct":"1","level":"1","hint":"","answer":"Th\u1eddi gian ch\u1ea1y trung bình c\u1ef1 li 100m c\u1ee7a các b\u1ea1n trong l\u1edbp là:<\/p>$\\overline{x}=\\dfrac{12.5+13.7+14.10+15.8+16.6}{36}\\approx14,08$<\/span> (giây)<\/p>Ch\u1ecdn A. <\/strong>14,08<\/span><\/p>","type":"choose","extra_type":"classic","user_id":"131","test":"0","date":"2023-05-27 01:57:39","option_type":"txt","len":0},{"id":"6592","mon_id":"1158767","chapter_id":"1158885","post_id":"6444","question":"\u0110i\u1ec3m (thang \u0111i\u1ec3m 100) c\u1ee7a 12 thí sinh cao \u0111i\u1ec3m nh\u1ea5t trong cu\u1ed9c thi nh\u01b0 sau:<\/p>58      74      92      81      97      88      75      69      87      69      75      77.<\/p>Ban t\u1ed5 ch\u1ee9c mu\u1ed1n trao các gi\u1ea3i Nh\u1ea5t, Nhì, Ba, T\u01b0 cho các thí sinh này, m\u1ed7i gi\u1ea3i trao cho 25% s\u1ed1 thí sinh (3 thí sinh). Xác \u0111\u1ecbnh các ng\u01b0\u1ee1ng \u0111i\u1ec3m \u0111\u1ec3 phân lo\u1ea1i thí sinh.<\/p>","options":["A. <\/strong>71,5","B.<\/strong> 72,5","C.<\/strong> 73,5","D.<\/strong> 74,5"],"correct":"2","level":"1","hint":"","answer":"S\u1eafp th\u1ee9 t\u1ef1 các s\u1ed1 li\u1ec7u trên thành dãy không gi\u1ea3m<\/p>58     69     69     74     75     75     77     81     87     88     92     97.<\/p>Gi\u1ea3i nh\u1ea5t dành cho các thí sinh \u0111\u1ea1t trên 87,5 \u0111i\u1ec3m.<\/p>Gi\u1ea3i nhì dành cho các thí sinh \u0111\u1ea1t trên 76 và d\u01b0\u1edbi 87,5 \u0111i\u1ec3m.<\/p>Gi\u1ea3i ba dành cho các thí sinh \u0111\u1ea1t trên 71,5 và d\u01b0\u1edbi 76 \u0111i\u1ec3m.<\/p>Gi\u1ea3i t\u01b0 dành cho các thí sinh \u0111\u1ea1t trên 58 và d\u01b0\u1edbi 71,5 \u0111i\u1ec3m.<\/p>Ch\u1ecdn B.<\/strong> 72,5<\/span><\/p>","type":"choose","extra_type":"shape2","user_id":"131","test":"0","date":"2023-05-27 02:04:39","option_type":"txt","len":0},{"id":"6596","mon_id":"1158767","chapter_id":"1158885","post_id":"6444","question":"B\u1ea3ng sau \u0111ây cho bi\u1ebft s\u1ed1 l\u1ea7n h\u1ecdc ti\u1ebfng Anh trên Internet trong m\u1ed9t tu\u1ea7n c\u1ee7a m\u1ed9t s\u1ed1 h\u1ecdc sinh l\u1edbp 10:<\/p><svg height=\"85\" width=\"400\"> <g><title><\/title><rect fill=\"#fff\" height=\"87\" id=\"canvas_background\" width=\"402\" x=\"-1\" y=\"-1\"><\/rect> <g display=\"none\" height=\"100%\" id=\"canvasGrid\" overflow=\"visible\" width=\"100%\" x=\"0\" y=\"0\"> <rect fill=\"url(#gridpattern)\" height=\"100%\" stroke-width=\"0\" width=\"100%\" x=\"0\" y=\"0\"><\/rect> <\/g> <\/g> <g><title><\/title><g id=\"svg_30\" stroke=\"null\"> <g id=\"svg_5\" stroke=\"null\"> <rect fill=\"#aad4ff\" height=\"39\" id=\"svg_1\" stroke=\"#000\" stroke-width=\"1.5\" width=\"108.00735\" x=\"0.01251\" y=\"2.23751\"><\/rect> <rect fill=\"#aad4ff\" height=\"39\" id=\"svg_2\" stroke=\"#000\" stroke-width=\"1.5\" width=\"108.00736\" x=\"0.01251\" y=\"41.23751\"><\/rect> <text fill=\"#000000\" font-family=\"Helvetica, Arial, sans-serif\" font-size=\"20\" id=\"svg_3\" stroke=\"#000\" stroke-width=\"0\" text-anchor=\"start\" transform=\"matrix(0.9730392098426819,0,0,1,0.00033740093255235637,0) \" x=\"3.01251\" xml:space=\"preserve\" y=\"31.23751\">S\u1ed1 l\u1ea7n<\/text> <text fill=\"#000000\" font-family=\"Helvetica, Arial, sans-serif\" font-size=\"20\" id=\"svg_4\" stroke=\"#000\" stroke-width=\"0\" text-anchor=\"start\" transform=\"matrix(0.9730392098426819,0,0,1,0.00033740093255235637,0) \" x=\"3.01251\" xml:space=\"preserve\" y=\"67.23751\">S\u1ed1 h\u1ecdc sinh<\/text> <\/g> <rect fill=\"#ffffff\" height=\"39\" id=\"svg_6\" stroke=\"#000\" stroke-opacity=\"null\" stroke-width=\"1.5\" width=\"48.65196\" x=\"108.01987\" y=\"2.23751\"><\/rect> <rect fill=\"#ffffff\" height=\"39\" id=\"svg_7\" stroke=\"#000\" stroke-opacity=\"null\" stroke-width=\"1.5\" width=\"48.65196\" x=\"108.01987\" y=\"41.23751\"><\/rect> <text fill=\"#000000\" font-family=\"Helvetica, Arial, sans-serif\" font-size=\"20\" id=\"svg_8\" stroke=\"#000\" stroke-opacity=\"null\" stroke-width=\"0\" text-anchor=\"start\" transform=\"matrix(0.9730392098426819,0,0,1,0.00033740093255235637,0) \" x=\"129.01252\" xml:space=\"preserve\" y=\"29.23751\">0\u200b\u200b<\/text> <text fill=\"#000000\" font-family=\"Helvetica, Arial, sans-serif\" font-size=\"20\" id=\"svg_9\" stroke=\"#000\" stroke-opacity=\"null\" stroke-width=\"0\" text-anchor=\"start\" transform=\"matrix(0.9730392098426819,0,0,1,0.00033740093255235637,0) \" x=\"129.01252\" xml:space=\"preserve\" y=\"66.23751\">2\u200b\u200b<\/text> <rect fill=\"#ffffff\" height=\"39\" id=\"svg_10\" stroke=\"#000\" stroke-opacity=\"null\" stroke-width=\"1.5\" width=\"48.65196\" x=\"156.67183\" y=\"2.23751\"><\/rect> <rect fill=\"#ffffff\" height=\"39\" id=\"svg_11\" stroke=\"#000\" stroke-opacity=\"null\" stroke-width=\"1.5\" width=\"48.65196\" x=\"156.67183\" y=\"41.23751\"><\/rect> <text fill=\"#000000\" font-family=\"Helvetica, Arial, sans-serif\" font-size=\"20\" id=\"svg_12\" stroke=\"#000\" stroke-opacity=\"null\" stroke-width=\"0\" text-anchor=\"start\" transform=\"matrix(0.9730392098426819,0,0,1,0.00033740093255235637,0) \" x=\"179.01252\" xml:space=\"preserve\" y=\"27.23751\">1\u200b\u200b<\/text> <text fill=\"#000000\" font-family=\"Helvetica, Arial, sans-serif\" font-size=\"20\" id=\"svg_13\" stroke=\"#000\" stroke-opacity=\"null\" stroke-width=\"0\" text-anchor=\"start\" transform=\"matrix(0.9730392098426819,0,0,1,0.00033740093255235637,0) \" x=\"179.01252\" xml:space=\"preserve\" y=\"66.23751\">4\u200b\u200b<\/text> <rect fill=\"#ffffff\" height=\"39\" id=\"svg_14\" stroke=\"#000\" stroke-opacity=\"null\" stroke-width=\"1.5\" width=\"48.65196\" x=\"204.35075\" y=\"2.23751\"><\/rect> <rect fill=\"#ffffff\" height=\"39\" id=\"svg_15\" stroke=\"#000\" stroke-opacity=\"null\" stroke-width=\"1.5\" width=\"48.65196\" x=\"204.35075\" y=\"41.23751\"><\/rect> <text fill=\"#000000\" font-family=\"Helvetica, Arial, sans-serif\" font-size=\"20\" id=\"svg_16\" stroke=\"#000\" stroke-opacity=\"null\" stroke-width=\"0\" text-anchor=\"start\" transform=\"matrix(0.9730392098426819,0,0,1,0.00033740093255235637,0) \" x=\"228.01252\" xml:space=\"preserve\" y=\"29.23751\">2\u200b\u200b<\/text> <text fill=\"#000000\" font-family=\"Helvetica, Arial, sans-serif\" font-size=\"20\" id=\"svg_17\" stroke=\"#000\" stroke-opacity=\"null\" stroke-width=\"0\" text-anchor=\"start\" transform=\"matrix(0.9730392098426819,0,0,1,0.00033740093255235637,0) \" x=\"228.01252\" xml:space=\"preserve\" y=\"66.23751\">6\u200b\u200b<\/text> <rect fill=\"#ffffff\" height=\"39\" id=\"svg_18\" stroke=\"#000\" stroke-opacity=\"null\" stroke-width=\"1.5\" width=\"48.65196\" x=\"252.02967\" y=\"2.23751\"><\/rect> <rect fill=\"#ffffff\" height=\"39\" id=\"svg_19\" stroke=\"#000\" stroke-opacity=\"null\" stroke-width=\"1.5\" width=\"48.65196\" x=\"252.02967\" y=\"41.23751\"><\/rect> <text fill=\"#000000\" font-family=\"Helvetica, Arial, sans-serif\" font-size=\"20\" id=\"svg_20\" stroke=\"#000\" stroke-opacity=\"null\" stroke-width=\"0\" text-anchor=\"start\" transform=\"matrix(0.9730392098426819,0,0,1,0.00033740093255235637,0) \" x=\"277.01252\" xml:space=\"preserve\" y=\"29.23751\">3\u200b\u200b<\/text> <text fill=\"#000000\" font-family=\"Helvetica, Arial, sans-serif\" font-size=\"20\" id=\"svg_21\" stroke=\"#000\" stroke-opacity=\"null\" stroke-width=\"0\" text-anchor=\"start\" transform=\"matrix(0.9730392098426819,0,0,1,0.00033740093255235637,0) \" x=\"272.01252\" xml:space=\"preserve\" y=\"66.23751\">12\u200b\u200b<\/text> <rect fill=\"#ffffff\" height=\"39\" id=\"svg_22\" stroke=\"#000\" stroke-opacity=\"null\" stroke-width=\"1.5\" width=\"48.65196\" x=\"300.68163\" y=\"2.23751\"><\/rect> <rect fill=\"#ffffff\" height=\"39\" id=\"svg_23\" stroke=\"#000\" stroke-opacity=\"null\" stroke-width=\"1.5\" width=\"48.65196\" x=\"300.68163\" y=\"41.23751\"><\/rect> <text fill=\"#000000\" font-family=\"Helvetica, Arial, sans-serif\" font-size=\"20\" id=\"svg_24\" stroke=\"#000\" stroke-opacity=\"null\" stroke-width=\"0\" text-anchor=\"start\" transform=\"matrix(0.9730392098426819,0,0,1,0.00033740093255235637,0) \" x=\"327.01252\" xml:space=\"preserve\" y=\"29.23751\">4\u200b\u200b<\/text> <text fill=\"#000000\" font-family=\"Helvetica, Arial, sans-serif\" font-size=\"20\" id=\"svg_25\" stroke=\"#000\" stroke-opacity=\"null\" stroke-width=\"0\" text-anchor=\"start\" transform=\"matrix(0.9730392098426819,0,0,1,0.00033740093255235637,0) \" x=\"327.01252\" xml:space=\"preserve\" y=\"66.23751\">8\u200b\u200b<\/text> <rect fill=\"#ffffff\" height=\"39\" id=\"svg_26\" stroke=\"#000\" stroke-opacity=\"null\" stroke-width=\"1.5\" width=\"48.65196\" x=\"348.36055\" y=\"2.23751\"><\/rect> <rect fill=\"#ffffff\" height=\"39\" id=\"svg_27\" stroke=\"#000\" stroke-opacity=\"null\" stroke-width=\"1.5\" width=\"48.65196\" x=\"348.36055\" y=\"41.23751\"><\/rect> <text fill=\"#000000\" font-family=\"Helvetica, Arial, sans-serif\" font-size=\"20\" id=\"svg_28\" stroke=\"#000\" stroke-opacity=\"null\" stroke-width=\"0\" text-anchor=\"start\" transform=\"matrix(0.9730392098426819,0,0,1,0.00033740093255235637,0) \" x=\"376.01252\" xml:space=\"preserve\" y=\"29.23751\">5\u200b\u200b<\/text> <text fill=\"#000000\" font-family=\"Helvetica, Arial, sans-serif\" font-size=\"20\" id=\"svg_29\" stroke=\"#000\" stroke-opacity=\"null\" stroke-width=\"0\" text-anchor=\"start\" transform=\"matrix(0.9730392098426819,0,0,1,0.00033740093255235637,0) \" x=\"376.01252\" xml:space=\"preserve\" y=\"66.23751\">3\u200b\u200b<\/text> <\/g> <\/g> <\/svg><\/span><\/p>Các t\u1ee9 phân v\u1ecb cho m\u1eabu s\u1ed1 li\u1ec7u này.<\/p>","options":["A.<\/strong> $Q_1=2,Q_2=3,Q_3=4$<\/span>","B.<\/strong> $Q_1=3,Q_2=2,Q_3=4$<\/span>","C.<\/strong> $Q_1=2,Q_2=4,Q_3=3$<\/span>","D.<\/strong> $Q_1=4,Q_2=3,Q_3=2$<\/span>"],"correct":"1","level":"1","hint":"","answer":"Vì n = 35 là s\u1ed1 l\u1ebb nên trung v\u1ecb là s\u1ed1 th\u1ee9 18: $Q_2=3$<\/span><\/span>.<\/p>Bên trái $Q_2$<\/span> có 17 s\u1ed1 li\u1ec7u nên trung v\u1ecb c\u1ee7a n\u1eeda này là s\u1ed1 th\u1ee9 9: $Q_1=2$<\/span><\/span>.<\/p>Bên ph\u1ea3i $Q_2$<\/span> có 17 s\u1ed1 li\u1ec7u nên trung v\u1ecb c\u1ee7a n\u1eeda này là s\u1ed1 th\u1ee9 27: $Q_3=4$<\/span><\/span>.<\/p>Ch\u1ecdn A.<\/strong> $Q_1=2,Q_2=3,Q_3=4$<\/span><\/span><\/p>","type":"choose","extra_type":"classic","user_id":"131","test":"0","date":"2023-05-27 02:17:39","option_type":"math","len":0}]}