[{"id":1926,"subject":"数学","grade":"七年级","stage":"初中","type":"选择题","content":"某班级为了了解学生最喜欢的课外活动，随机抽取了40名学生进行调查，并将结果整理成如下频数分布表：\n\n| 活动类型 | 频数 |\n|----------|------|\n| 阅读 | 8 |\n| 运动 | 15 |\n| 绘画 | 6 |\n| 音乐 | 11 |\n\n若该班级共有200名学生，估计喜欢运动的学生人数最接近以下哪个数值？","answer":"C","explanation":"根据频数分布表，40名学生中有15人最喜欢运动，所占比例为 15 ÷ 40 = 0.375。用此比例估计整个班级200名学生中喜欢运动的人数：200 × 0.375 = 75。因此，估计喜欢运动的学生人数最接近75人，正确答案为C。","solution_steps":"","common_mistakes":"","learning_suggestions":"","difficulty":"简单","points":1,"is_active":1,"created_at":"2026-01-07 13:16:48","updated_at":"2026-01-07 13:16:48","sort_order":0,"source":null,"tags":null,"analysis":null,"knowledge_point":null,"difficulty_coefficient":null,"suggested_time":null,"accuracy_rate":null,"usage_count":0,"last_used":null,"view_count":0,"favorite_count":0,"options":[{"id":"A","content":"50","is_correct":0},{"id":"B","content":"65","is_correct":0},{"id":"C","content":"75","is_correct":1},{"id":"D","content":"85","is_correct":0}]},{"id":578,"subject":"数学","grade":"初一","stage":"小学","type":"选择题","content":"26","answer":"待完善","explanation":"解析待完善","solution_steps":null,"common_mistakes":null,"learning_suggestions":null,"difficulty":"简单","points":1,"is_active":1,"created_at":"2025-12-29 20:04:45","updated_at":"2025-12-30 11:11:27","sort_order":0,"source":null,"tags":null,"analysis":null,"knowledge_point":null,"difficulty_coefficient":null,"suggested_time":null,"accuracy_rate":null,"usage_count":0,"last_used":null,"view_count":0,"favorite_count":0,"options":[]},{"id":2516,"subject":"数学","grade":"九年级","stage":"初中","type":"选择题","content":"某学生设计了一个圆形花坛，其周长为6π米。现计划在花坛外侧修建一条宽度为1米的环形步道，则这条步道的面积是多少平方米？","answer":"A","explanation":"首先根据圆的周长公式C = 2πr，由已知周长6π米可得：2πr = 6π，解得半径r = 3米。这是花坛的内半径。步道宽1米，因此包含步道后的外圆半径为3 + 1 = 4米。步道的面积等于外圆面积减去内圆面积：π×(4²) - π×(3²) = 16π - 9π = 7π（平方米）。因此正确答案是A。","solution_steps":"","common_mistakes":"","learning_suggestions":"","difficulty":"简单","points":1,"is_active":1,"created_at":"2026-01-10 15:47:00","updated_at":"2026-01-10 15:47:00","sort_order":0,"source":null,"tags":null,"analysis":null,"knowledge_point":null,"difficulty_coefficient":null,"suggested_time":null,"accuracy_rate":null,"usage_count":0,"last_used":null,"view_count":0,"favorite_count":0,"options":[{"id":"A","content":"7π","is_correct":1},{"id":"B","content":"8π","is_correct":0},{"id":"C","content":"9π","is_correct":0},{"id":"D","content":"10π","is_correct":0}]},{"id":749,"subject":"数学","grade":"初一","stage":"小学","type":"填空题","content":"在一次班级大扫除中，某学生负责统计清洁工具的分配情况。已知每2名学生共用1把扫帚，每3名学生共用1个拖把，每4名学生共用1个水桶。如果总共使用了26件清洁工具，那么参加大扫除的学生人数是___人。","answer":"24","explanation":"设参加大扫除的学生人数为x。根据题意，扫帚的数量为x\/2，拖把的数量为x\/3，水桶的数量为x\/4。总工具数为26件，因此可列方程：x\/2 + x\/3 + x\/4 = 26。通分后得(6x + 4x + 3x)\/12 = 26，即13x\/12 = 26。两边同乘以12，得13x = 312，解得x = 24。因此，参加大扫除的学生人数是24人。","solution_steps":null,"common_mistakes":null,"learning_suggestions":null,"difficulty":"简单","points":1,"is_active":1,"created_at":"2025-12-29 23:22:54","updated_at":"2025-12-30 11:11:27","sort_order":0,"source":null,"tags":null,"analysis":null,"knowledge_point":null,"difficulty_coefficient":null,"suggested_time":null,"accuracy_rate":null,"usage_count":0,"last_used":null,"view_count":0,"favorite_count":0,"options":[]},{"id":2453,"subject":"数学","grade":"八年级","stage":"初中","type":"填空题","content":"某班级在一次数学测验中，10名学生的成绩分别为：82, 76, 90, 88, 79, 85, 92, 85, 80, 85。这组数据的众数是___，中位数是___。","answer":"85, 84.5","explanation":"众数是出现次数最多的数，85出现3次，最多；将数据从小到大排列后，第5和第6个数为80和89，中位数为(80+89)÷2=84.5。","solution_steps":"","common_mistakes":"","learning_suggestions":"","difficulty":"中等","points":1,"is_active":1,"created_at":"2026-01-10 13:57:25","updated_at":"2026-01-10 13:57:25","sort_order":0,"source":null,"tags":null,"analysis":null,"knowledge_point":null,"difficulty_coefficient":null,"suggested_time":null,"accuracy_rate":null,"usage_count":0,"last_used":null,"view_count":0,"favorite_count":0,"options":[]},{"id":539,"subject":"数学","grade":"初一","stage":"初中","type":"选择题","content":"在一次班级环保活动中，某学生收集了若干节废旧电池。他将这些电池按每5节装一盒，发现最后剩下2节；如果改为每7节装一盒，则刚好装完，没有剩余。已知他收集的电池总数在30到50之间，那么他一共收集了多少节电池？","answer":"C","explanation":"设该学生收集的电池总数为x节。根据题意：\n1. 每5节装一盒，剩下2节，说明 x 除以5余2，即 x ≡ 2 (mod 5)；\n2. 每7节装一盒，刚好装完，说明 x 能被7整除，即 x ≡ 0 (mod 7)；\n3. 且 30 < x < 50。\n\n在30到50之间，7的倍数有：35、42、49。\n- 35 ÷ 5 = 7 余 0 → 不符合“余2”的条件；\n- 42 ÷ 5 = 8 余 2 → 符合余2的条件；\n- 49 ÷ 5 = 9 余 4 → 不符合。\n\n因此，只有42同时满足被7整除、被5除余2，并且在30到50之间。\n故正确答案是C。","solution_steps":null,"common_mistakes":null,"learning_suggestions":null,"difficulty":"简单","points":1,"is_active":1,"created_at":"2025-12-29 18:51:32","updated_at":"2025-12-30 11:11:27","sort_order":0,"source":null,"tags":null,"analysis":null,"knowledge_point":null,"difficulty_coefficient":null,"suggested_time":null,"accuracy_rate":null,"usage_count":0,"last_used":null,"view_count":0,"favorite_count":0,"options":[{"id":"A","content":"35","is_correct":0},{"id":"B","content":"37","is_correct":0},{"id":"C","content":"42","is_correct":1},{"id":"D","content":"47","is_correct":0}]},{"id":2291,"subject":"数学","grade":"七年级","stage":"初中","type":"填空题","content":"在数轴上，点A表示的数是-3，点B与点A的距离为7个单位长度，且点B在原点右侧。点C是线段AB的中点，点D与点C的距离为4个单位长度，且点D在点C的左侧。那么点D表示的数是___。","answer":"-3.5","explanation":"点A表示-3，点B在原点右侧且与A相距7个单位，因此点B表示的数为-3 + 7 = 4。点C是AB的中点，坐标为(-3 + 4) ÷ 2 = 0.5。点D在点C左侧4个单位，因此点D表示的数为0.5 - 4 = -3.5。","solution_steps":"","common_mistakes":"","learning_suggestions":"","difficulty":"困难","points":1,"is_active":1,"created_at":"2026-01-09 16:44:29","updated_at":"2026-01-09 16:44:29","sort_order":0,"source":null,"tags":null,"analysis":null,"knowledge_point":null,"difficulty_coefficient":null,"suggested_time":null,"accuracy_rate":null,"usage_count":0,"last_used":null,"view_count":0,"favorite_count":0,"options":[]},{"id":715,"subject":"数学","grade":"初一","stage":"初中","type":"填空题","content":"某学生测量了家中客厅地砖的边长，发现每块地砖都是边长为0.6米的正方形。若客厅的长边铺了8块地砖，宽边铺了5块地砖，则客厅的总面积是______平方米。","answer":"14.4","explanation":"每块地砖是边长为0.6米的正方形，因此每块地砖的面积为 0.6 × 0.6 = 0.36 平方米。客厅长边铺了8块，宽边铺了5块，说明总共铺了 8 × 5 = 40 块地砖。因此客厅的总面积为 40 × 0.36 = 14.4 平方米。本题考查几何图形初步中的面积计算，结合有理数乘法运算，符合七年级数学课程要求。","solution_steps":null,"common_mistakes":null,"learning_suggestions":null,"difficulty":"简单","points":1,"is_active":1,"created_at":"2025-12-29 22:50:03","updated_at":"2025-12-30 11:11:27","sort_order":0,"source":null,"tags":null,"analysis":null,"knowledge_point":null,"difficulty_coefficient":null,"suggested_time":null,"accuracy_rate":null,"usage_count":0,"last_used":null,"view_count":0,"favorite_count":0,"options":[]},{"id":564,"subject":"数学","grade":"初一","stage":"初中","type":"选择题","content":"在一次班级数学测验中，某学生记录了5名同学的数学成绩（单位：分）分别为：85，90，78，92，85。如果老师决定将每位同学的成绩都增加5分，那么这组数据的中位数会如何变化？","answer":"A","explanation":"首先将原始数据从小到大排列：78，85，85，90，92。共有5个数据，中位数是中间的那个数，即第3个数，为85分。当每位同学的成绩都增加5分后，新的数据为：83，90，90，95，97。重新排序后为：83，90，90，95，97，中位数是第3个数，即90分。90 - 85 = 5，因此中位数增加了5分。所以正确答案是A。","solution_steps":null,"common_mistakes":null,"learning_suggestions":null,"difficulty":"简单","points":1,"is_active":1,"created_at":"2025-12-29 19:31:22","updated_at":"2025-12-30 11:11:27","sort_order":0,"source":null,"tags":null,"analysis":null,"knowledge_point":null,"difficulty_coefficient":null,"suggested_time":null,"accuracy_rate":null,"usage_count":0,"last_used":null,"view_count":0,"favorite_count":0,"options":[{"id":"A","content":"增加5分","is_correct":1},{"id":"B","content":"增加10分","is_correct":0},{"id":"C","content":"不变","is_correct":0},{"id":"D","content":"无法确定","is_correct":0}]},{"id":315,"subject":"数学","grade":"初一","stage":"初中","type":"选择题","content":"在一次班级数学测验中，某学生记录了5名同学的成绩分别为：82分、76分、90分、88分和74分。如果老师决定将每位同学的成绩都加上5分作为鼓励，那么这5名同学成绩的平均分会增加多少？","answer":"A","explanation":"原5名同学的成绩总和为：82 + 76 + 90 + 88 + 74 = 410（分），平均分为410 ÷ 5 = 82（分）。每位同学加5分后，总成绩增加5 × 5 = 25（分），新的总分为410 + 25 = 435（分），新的平均分为435 ÷ 5 = 87（分）。因此，平均分增加了87 - 82 = 5（分）。也可以直接理解：当每个数据都增加相同的数值时，平均数也增加相同的数值。所以平均分增加5分。","solution_steps":null,"common_mistakes":null,"learning_suggestions":null,"difficulty":"简单","points":1,"is_active":1,"created_at":"2025-12-29 15:36:16","updated_at":"2025-12-30 11:11:27","sort_order":0,"source":null,"tags":null,"analysis":null,"knowledge_point":null,"difficulty_coefficient":null,"suggested_time":null,"accuracy_rate":null,"usage_count":0,"last_used":null,"view_count":0,"favorite_count":0,"options":[{"id":"A","content":"5分","is_correct":1},{"id":"B","content":"10分","is_correct":0},{"id":"C","content":"1分","is_correct":0},{"id":"D","content":"平均分不变","is_correct":0}]}]