[{"id":1970,"subject":"数学","grade":"七年级","stage":"初中","type":"选择题","content":"某学生在研究某次校园环保活动中各班收集的废旧纸张重量时，记录了六个班级的数据（单位：千克）：18.3, 22.7, 19.5, 25.1, 20.8, 23.6。为了分析这组数据的分布特征，该学生先将数据按从小到大的顺序排列，然后计算了上四分位数（Q3）和下四分位数（Q1），并求出四分位距（IQR = Q3 - Q1）。已知在计算四分位数时，若数据个数为偶数，则Q1为前半部分数据的中位数，Q3为后半部分数据的中位数。请问这组数据的四分位距最接近以下哪个数值？","answer":"B","explanation":"本题考查数据的收集、整理与描述中四分位距（IQR）的计算方法。首先将六个班级的废旧纸张重量数据从小到大排序：18.3, 19.5, 20.8, 22.7, 23.6, 25.1。由于数据个数为6（偶数），将数据分为前后两半：前半部分为18.3, 19.5, 20.8，后半部分为22.7, 23.6, 25.1。下四分位数Q1是前半部分的中位数，即19.5；上四分位数Q3是后半部分的中位数，即23.6。因此，四分位距IQR = Q3 - Q1 = 23.6 - 19.5 = 4.1，最接近选项B中的4.2。","solution_steps":"","common_mistakes":"","learning_suggestions":"","difficulty":"中等","points":1,"is_active":1,"created_at":"2026-01-07 14:49:03","updated_at":"2026-01-07 14:49:03","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":"3.8","is_correct":0},{"id":"B","content":"4.2","is_correct":1},{"id":"C","content":"4.6","is_correct":0},{"id":"D","content":"5.0","is_correct":0}]},{"id":2192,"subject":"数学","grade":"七年级","stage":"初中","type":"选择题","content":"某学生在记录一周内每天气温变化时，发现某天的气温比前一天上升了5℃，记作+5℃。如果第二天的气温又比当天下降了8℃，那么第二天的气温变化应记作多少？","answer":"B","explanation":"气温下降应使用负数表示。题目中明确指出‘下降了8℃’，因此变化量应记为-8℃。选项B正确。其他选项中，A表示上升，C和D是数值计算错误或符号错误，不符合题意。","solution_steps":"","common_mistakes":"","learning_suggestions":"","difficulty":"简单","points":1,"is_active":1,"created_at":"2026-01-09 14:25:31","updated_at":"2026-01-09 14:25:31","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":"+8℃","is_correct":0},{"id":"B","content":"-8℃","is_correct":1},{"id":"C","content":"+3℃","is_correct":0},{"id":"D","content":"-3℃","is_correct":0}]},{"id":2287,"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-5，点B与点A之间的距离是8个单位长度，且点B位于点A的右侧，那么点B表示的数是___。","answer":"3","explanation":"根据题意，点A表示-5，点B在点A右侧且距离为8个单位长度。在数轴上向右移动表示数值增加，因此点B表示的数为-5 + 8 = 3。","solution_steps":"","common_mistakes":"","learning_suggestions":"","difficulty":"简单","points":1,"is_active":1,"created_at":"2026-01-09 16:27:46","updated_at":"2026-01-09 16:27:46","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":633,"subject":"数学","grade":"初一","stage":"初中","type":"选择题","content":"某班级组织植树活动，计划在一条笔直的小路一侧每隔5米种一棵树，起点和终点都种。如果一共种了13棵树，那么这条小路的长度是多少米？","answer":"A","explanation":"这是一道结合实际情境的一元一次方程应用题，考查学生对植树问题中间隔数与棵数关系的理解。已知每隔5米种一棵树，起点和终点都种，共种13棵树。由于两端都种树，间隔数 = 棵数 - 1 = 13 - 1 = 12（个）。每个间隔5米，因此总长度为 12 × 5 = 60（米）。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 21:57:45","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":"A","content":"60米","is_correct":1},{"id":"B","content":"65米","is_correct":0},{"id":"C","content":"55米","is_correct":0},{"id":"D","content":"70米","is_correct":0}]},{"id":2206,"subject":"数学","grade":"七年级","stage":"初中","type":"选择题","content":"某学生记录了连续五天的气温变化情况，以0℃为标准，高于0℃记为正，低于0℃记为负。其中三天的气温分别为：+3℃、-2℃、-5℃。这三天气温中，哪一天的气温最低？","answer":"C","explanation":"在正数和负数中，负数的绝对值越大，表示温度越低。比较-2和-5，-5比-2更小，因此-5℃的那天温度最低。正数+3℃高于0℃，显然不是最低。因此正确答案是C。","solution_steps":"","common_mistakes":"","learning_suggestions":"","difficulty":"简单","points":1,"is_active":1,"created_at":"2026-01-09 14:25:31","updated_at":"2026-01-09 14:25:31","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":"+3℃的那天","is_correct":0},{"id":"B","content":"-2℃的那天","is_correct":0},{"id":"C","content":"-5℃的那天","is_correct":0},{"id":"D","content":"无法确定","is_correct":0}]},{"id":450,"subject":"数学","grade":"初一","stage":"小学","type":"选择题","content":"某学生在整理班级同学的课外阅读时间数据时，记录了10名学生每周的阅读时间（单位：小时）如下：3, 5, 4, 6, 4, 7, 5, 4, 6, 5。为了分析数据，他计算了这组数据的众数。请问这组数据的众数是多少？","answer":"C","explanation":"众数是一组数据中出现次数最多的数。首先统计每个数出现的次数：3出现1次，4出现3次，5出现3次，6出现2次，7出现1次。可以看出，4和5都出现了3次，是出现次数最多的数，因此这组数据的众数是4和5。当一组数据中有两个数出现次数相同且最多时，这两个数都是众数。所以正确答案是C。","solution_steps":null,"common_mistakes":null,"learning_suggestions":null,"difficulty":"简单","points":1,"is_active":1,"created_at":"2025-12-29 17:44:45","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":"A","content":"4","is_correct":0},{"id":"B","content":"5","is_correct":0},{"id":"C","content":"4和5","is_correct":1},{"id":"D","content":"6","is_correct":0}]},{"id":161,"subject":"数学","grade":"初一","stage":"初中","type":"选择题","content":"已知一次函数 $ y = 2x - 3 $，若点 $ (a, 5) $ 在该函数的图像上，则 $ a $ 的值是（ ）。","answer":"B","explanation":"因为点 $ (a, 5) $ 在一次函数 $ y = 2x - 3 $ 的图像上，所以将 $ y = 5 $ 代入函数解析式，得到方程：$ 5 = 2a - 3 $。解这个方程：两边同时加3，得 $ 8 = 2a $，再两边同时除以2，得 $ a = 4 $。因此正确答案是B。","solution_steps":"","common_mistakes":"","learning_suggestions":"","difficulty":"中等","points":1,"is_active":1,"created_at":"2025-12-24 12:00:27","updated_at":"2025-12-24 12:00:27","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":"1","is_correct":0},{"id":"B","content":"4","is_correct":1},{"id":"C","content":"-1","is_correct":0},{"id":"D","content":"3","is_correct":0}]},{"id":1034,"subject":"数学","grade":"初一","stage":"小学","type":"填空题","content":"在一次班级环保活动中，某学生记录了连续5天每天收集的废旧纸张重量（单位：千克），分别为2.5、3.0、2.8、3.2和2.7。如果这些数据被用来制作频数分布表，并将数据按0.5千克为组距进行分组，那么重量在2.5千克到3.0千克（含2.5千克，不含3.0千克）这一组中的数据个数是____。","answer":"3","explanation":"首先确定分组区间：以0.5千克为组距，从2.5开始分组，则分组为[2.5, 3.0)、[3.0, 3.5)等。题目要求统计落在[2.5, 3.0)区间内的数据个数。原始数据为2.5、3.0、2.8、3.2、2.7。其中，2.5、2.8、2.7均大于等于2.5且小于3.0，共3个数据；而3.0属于下一组[3.0, 3.5)，不计入本组。因此，该组中有3个数据。","solution_steps":null,"common_mistakes":null,"learning_suggestions":null,"difficulty":"简单","points":1,"is_active":1,"created_at":"2025-12-30 06:01:33","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":168,"subject":"数学","grade":"初一","stage":"小学","type":"选择题","content":"小明去文具店买笔记本，每本笔记本的价格是8元。他买了3本，付给收银员50元，应找回多少元？","answer":"A","explanation":"首先计算3本笔记本的总价：8元\/本 × 3本 = 24元。小明付了50元，所以应找回的钱为：50元 - 24元 = 26元。因此正确答案是A。","solution_steps":null,"common_mistakes":null,"learning_suggestions":null,"difficulty":"简单","points":1,"is_active":1,"created_at":"2025-12-29 11:20:30","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":"26元","is_correct":1},{"id":"B","content":"24元","is_correct":0},{"id":"C","content":"34元","is_correct":0},{"id":"D","content":"16元","is_correct":0}]},{"id":2395,"subject":"数学","grade":"八年级","stage":"初中","type":"选择题","content":"某学生在一张方格纸上绘制了一个轴对称图形，其对称轴为直线x = 3。已知该图形上一点P的坐标为(1, 5)，则其对称点P′的坐标为多少？若该图形还满足：连接P与P′的线段中点在对称轴上，且线段PP′与x轴垂直，那么以下选项中正确的是？","answer":"A","explanation":"由于图形关于直线x = 3轴对称，点P(1, 5)的对称点P′应与P到对称轴的距离相等，且在对称轴另一侧。点P到直线x = 3的水平距离为|3 - 1| = 2，因此P′的横坐标为3 + 2 = 5，纵坐标保持不变（因为对称轴是竖直的，上下不翻转），故P′的坐标为(5, 5)。同时，PP′的中点横坐标为(1 + 5)\/2 = 3，恰好在对称轴x = 3上，且PP′为水平线段，与x轴平行而非垂直——但题目中‘与x轴垂直’应为笔误或干扰信息，实际轴对称中对应点连线被对称轴垂直平分，此处对称轴为竖直，PP′为水平，确实互相垂直，条件成立。因此正确答案为A。","solution_steps":"","common_mistakes":"","learning_suggestions":"","difficulty":"中等","points":1,"is_active":1,"created_at":"2026-01-10 11:54:32","updated_at":"2026-01-10 11:54:32","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":"P′的坐标为(5, 5)","is_correct":1},{"id":"B","content":"P′的坐标为(3, 5)","is_correct":0},{"id":"C","content":"P′的坐标为(5, 1)","is_correct":0},{"id":"D","content":"P′的坐标为(1, 3)","is_correct":0}]}]