某学生在整理班级同学的课外阅读情况时,收集了10名同学每周课外阅读时间(单位:小时),数据如下:3,5,4,6,5,7,5,4,6,5。这组数据的众数和中位数分别是多少?
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[{"id":2178,"content":"某学生在数轴上标记了三个有理数 a、b、c,其中 a = -2.5,b 是 a 的相反数,c 是 b 与 1.5 的和。若将这三个数按从小到大的顺序排列,正确的是:","type":"选择题","subject":"数学","grade":"七年级","stage":"初中","difficulty":"中等","answer":"B","explanation":"首先,a = -2.5;b 是 a 的相反数,因此 b = 2.5;c 是 b 与 1.5 的和,即 c = 2.5 + 1.5 = 4。三个数分别为:a = -2.5,b = 2.5,c = 4。在数轴上,-2.5 < 2.5 < 4,因此从小到大的顺序是 a < b < c,对应选项 B。","options":[{"id":"A","content":"a < c < b"},{"id":"B","content":"a < b < c"},{"id":"C","content":"c < a < b"},{"id":"D","content":"b < c < a"}]},{"id":6,"content":"下列现象中,属于光的反射现象的是?","type":"选择题","subject":"物理","grade":"初二","stage":"初中","difficulty":"简单","answer":"C","explanation":"平面镜成像是光的反射现象,水中倒影也是光的反射现象。","options":[{"id":"A","content":"日食和月食"},{"id":"B","content":"小孔成像"},{"id":"C","content":"平面镜成像"},{"id":"D","content":"海市蜃楼"}]},{"id":309,"content":"某班级在一次数学测验中,收集了30名学生的成绩(单位:分),并将数据整理如下:90分以上有8人,80~89分有12人,70~79分有6人,60~69分有3人,60分以下有1人。请问这次测验中,成绩在80分及以上的学生所占的百分比是多少?","type":"选择题","subject":"数学","grade":"初一","stage":"初中","difficulty":"简单","answer":"D","explanation":"首先确定80分及以上的学生人数:90分以上有8人,80~89分有12人,因此80分及以上共有8 + 12 = 20人。总人数为30人。所求百分比为(20 ÷ 30) × 100% ≈ 66.7%。因此正确答案是D。本题考查数据的收集、整理与描述中百分比的计算,属于简单难度。","options":[{"id":"A","content":"40%"},{"id":"B","content":"50%"},{"id":"C","content":"60%"},{"id":"D","content":"66.7%"}]},{"id":2306,"content":"某公园计划修建一个等腰三角形花坛,设计要求其底边长为8米,两腰相等且长度为5米。为了确保结构稳定,工程师需要在花坛内部从顶点向底边作一条垂直线段作为支撑。这条支撑线的长度是多少?","type":"选择题","subject":"数学","grade":"八年级","stage":"初中","difficulty":"简单","answer":"A","explanation":"本题考查勾股定理在等腰三角形中的应用。已知等腰三角形底边为8米,两腰为5米。从顶点向底边作垂线,这条垂线既是高,也是底边的中线(等腰三角形三线合一),因此将底边分为两个4米长的线段。由此可构造一个直角三角形,其中斜边为腰长5米,一条直角边为4米,另一条直角边即为所求的高h。根据勾股定理:h² + 4² = 5²,即h² + 16 = 25,解得h² = 9,所以h = 3米。因此正确答案为A。","options":[{"id":"A","content":"3米"},{"id":"B","content":"4米"},{"id":"C","content":"√21米"},{"id":"D","content":"√39米"}]},{"id":2038,"content":"如图,在平面直角坐标系中,点 A(0, 4)、B(3, 0)、C(0, 0) 构成直角三角形 △ABC,∠C = 90°。将 △ABC 沿直线 y = x 翻折得到 △A'B'C',则点 B' 的坐标是( )","type":"选择题","subject":"数学","grade":"八年级","stage":"初中","difficulty":"中等","answer":"A","explanation":"本题综合考查了勾股定理、轴对称变换与坐标几何知识。首先确认 △ABC 是以 C 为直角顶点的直角三角形,其中 AC = 4,BC = 3,AB = 5(由勾股定理可得)。题目要求将整个三角形沿直线 y = x 翻折,即关于直线 y = x 作轴对称变换。在平面直角坐标系中,一个点 (a, b) 关于直线 y = x 的对称点为 (b, a)。因此,点 B(3, 0) 翻折后的对应点 B' 的坐标为 (0, 3)。验证其他点:A(0,4) → A'(4,0),C(0,0) → C'(0,0),符合对称规律。故正确答案为 A。","options":[{"id":"A","content":"(0, 3)"},{"id":"B","content":"(3, 0)"},{"id":"C","content":"(0, -3)"},{"id":"D","content":"(-3, 0)"}]},{"id":2270,"content":"在数轴上,点A表示的数是-3,点B与点A的距离是7个单位长度,且点B在原点右侧。若点C表示的数是点B表示的数的相反数,则点C在数轴上的位置是","type":"选择题","subject":"数学","grade":"七年级","stage":"初中","difficulty":"中等","answer":"D","explanation":"点A表示-3,点B在点A右侧7个单位,因此点B表示的数为-3 + 7 = 4。点C是点B的相反数,即-4。-4位于原点左侧,距离原点4个单位长度。因此正确答案是D。","options":[{"id":"A","content":"在原点左侧,距离原点4个单位长度"},{"id":"B","content":"在原点左侧,距离原点10个单位长度"},{"id":"C","content":"在原点左侧,距离原点7个单位长度"},{"id":"D","content":"在原点左侧,距离原点4个单位长度"}]},{"id":651,"content":"在一次班级环保活动中,某学生收集了若干个塑料瓶。如果他将这些瓶子平均分给5个小组,每组得到8个,还剩下3个;如果他想让每组得到10个,则需要再收集___个瓶子才能正好分完。","type":"填空题","subject":"数学","grade":"初一","stage":"初中","difficulty":"简单","answer":"7","explanation":"首先根据题意,设该学生原来收集的瓶子总数为x。由‘平均分给5个小组,每组8个,还剩3个’可得:x = 5 × 8 + 3 = 43。若每组要分到10个,则总共需要5 × 10 = 50个瓶子。因此还需要收集的瓶子数为50 - 43 = 7个。本题考查一元一次方程的实际应用,通过建立等量关系求解未知量,符合七年级数学课程要求。","options":[]},{"id":1807,"content":"某学生在整理班级数学测验成绩时,发现前5名学生的分数分别为82、88、90、88、92。这组数据的众数和中位数分别是多少?","type":"选择题","subject":"数学","grade":"八年级","stage":"初中","difficulty":"简单","answer":"A","explanation":"首先将数据从小到大排列:82、88、88、90、92。众数是出现次数最多的数,88出现了两次,其他数各出现一次,因此众数是88。中位数是数据按顺序排列后位于中间的数,共有5个数据,中间位置是第3个数,即88。因此中位数也是88。正确答案是A。","options":[{"id":"A","content":"众数是88,中位数是88"},{"id":"B","content":"众数是90,中位数是88"},{"id":"C","content":"众数是88,中位数是90"},{"id":"D","content":"众数是92,中位数是90"}]},{"id":559,"content":"18","type":"选择题","subject":"数学","grade":"初一","stage":"小学","difficulty":"简单","answer":"待完善","explanation":"解析待完善","options":[]},{"id":539,"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?","type":"选择题","subject":"数学","grade":"初一","stage":"初中","difficulty":"简单","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。","options":[{"id":"A","content":"35"},{"id":"B","content":"37"},{"id":"C","content":"42"},{"id":"D","content":"47"}]}]