在某次班级大扫除中,学生们被分成若干小组清理教室。如果每组安排5人,则多出3人;如果每组安排6人,则最后一组只有4人。这个班级共有___名学生。
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首先将数据按从小到大的顺序排列:1,1,2,2,2,2,3,3,4,5。共有10个数据,是偶数个,因此中位数是中间两个数的平均数。中间两个数是第5个和第6个,都是2,所以中位数为 (2 + 2) ÷ 2 = 2。因此正确答案是A。
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[{"id":2241,"content":"某学生在数轴上从原点出发,先向右移动8个单位长度,再向左移动12个单位长度,接着向右移动5个单位长度,最后向左移动3个单位长度。此时该学生所在位置的数是___。","type":"填空题","subject":"数学","grade":"七年级","stage":"初中","difficulty":"困难","answer":"-2","explanation":"向右移动表示加上正数,向左移动表示加上负数。计算过程为:0 + 8 + (-12) + 5 + (-3) = (8 + 5) + (-12 - 3) = 13 - 15 = -2。因此最终位置对应的数是-2。","options":[]},{"id":636,"content":"在一次环保活动中,某学校七年级学生共收集了120千克废纸。其中,A班收集的废纸比B班多10千克,且两班收集的废纸总量正好是全年级收集量的一半。设B班收集的废纸为x千克,则根据题意可列方程为:","type":"选择题","subject":"数学","grade":"初一","stage":"初中","difficulty":"简单","answer":"A","explanation":"题目中说明A班比B班多收集10千克,B班收集了x千克,则A班收集了(x + 10)千克。两班共收集的废纸是全年级的一半,全年级共收集120千克,因此两班共收集120 ÷ 2 = 60千克。所以可列方程:x + (x + 10) = 60。选项A正确。选项B错误地将总量设为120;选项C错误地将A班的收集量表示为10x;选项D虽然表达式正确,但等式右边应为60而非120。","options":[{"id":"A","content":"x + (x + 10) = 60"},{"id":"B","content":"x + (x - 10) = 120"},{"id":"C","content":"x + 10x = 60"},{"id":"D","content":"x + (x + 10) = 120"}]},{"id":2304,"content":"在一次数学实践活动中,某学生用一根长度为20 cm的铁丝围成一个等腰三角形。已知底边长为6 cm,则这个等腰三角形的腰长是多少?","type":"选择题","subject":"数学","grade":"八年级","stage":"初中","difficulty":"简单","answer":"B","explanation":"等腰三角形有两条相等的腰和一条底边。已知铁丝总长为20 cm,即三角形的周长为20 cm,底边长为6 cm。设腰长为x cm,则根据周长公式可得:2x + 6 = 20。解这个方程:2x = 20 - 6 = 14,所以x = 7。因此,腰长为7 cm。选项B正确。","options":[{"id":"A","content":"6 cm"},{"id":"B","content":"7 cm"},{"id":"C","content":"8 cm"},{"id":"D","content":"10 cm"}]},{"id":245,"content":"某学生计算一个数的相反数时,将该数加上3,结果得到8,那么这个数的相反数是____。","type":"填空题","subject":"数学","grade":"初一","stage":"小学","difficulty":"简单","answer":"-5","explanation":"设这个数为x。根据题意,某学生将这个数加上3得到8,即x + 3 = 8,解得x = 5。那么这个数的相反数是-5。题目考查的是相反数的概念和一元一次方程的简单应用,符合七年级数学课程内容。","options":[]},{"id":1006,"content":"某班级组织植树活动,若每名学生种3棵树,则还剩10棵树没人种;若每名学生种4棵树,则最后一名学生只需种2棵树。这个班级共有___名学生。","type":"填空题","subject":"数学","grade":"初一","stage":"初中","difficulty":"简单","answer":"12","explanation":"设这个班级共有x名学生。根据题意,树的总数不变。第一种情况:每名学生种3棵,还剩10棵,所以总树数为3x + 10。第二种情况:前(x - 1)名学生每人种4棵,最后一名学生种2棵,总树数为4(x - 1) + 2 = 4x - 4 + 2 = 4x - 2。因为树的数量相同,列方程:3x + 10 = 4x - 2。解这个一元一次方程:移项得10 + 2 = 4x - 3x,即12 = x。所以这个班级共有12名学生。","options":[]},{"id":332,"content":"某班级在一次数学测验中,随机抽取了10名学生的成绩(单位:分)如下:78, 85, 88, 92, 76, 85, 90, 85, 82, 87。这组数据的众数是多少?","type":"选择题","subject":"数学","grade":"初一","stage":"初中","difficulty":"简单","answer":"B","explanation":"众数是一组数据中出现次数最多的数。观察给出的数据:78, 85, 88, 92, 76, 85, 90, 85, 82, 87。统计每个数出现的次数:76出现1次,78出现1次,82出现1次,85出现3次,87出现1次,88出现1次,90出现1次,92出现1次。其中85出现的次数最多,共3次,因此这组数据的众数是85。","options":[{"id":"A","content":"76"},{"id":"B","content":"85"},{"id":"C","content":"87"},{"id":"D","content":"90"}]},{"id":185,"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5本,付给收银员50元。请问他应找回多少钱?","type":"选择题","subject":"数学","grade":"初一","stage":"小学","difficulty":"简单","answer":"A","explanation":"首先计算小明购买5本笔记本的总花费:每本8元,5本就是 8 × 5 = 40 元。他付了50元,所以应找回的钱是 50 - 40 = 10 元。因此正确答案是A。","options":[{"id":"A","content":"10元"},{"id":"B","content":"12元"},{"id":"C","content":"15元"},{"id":"D","content":"18元"}]},{"id":310,"content":"某学生记录了连续5天的气温变化情况,每天的气温分别为-2℃、0℃、3℃、-1℃、4℃。这5天气温的平均值是多少?","type":"选择题","subject":"数学","grade":"初一","stage":"小学","difficulty":"简单","answer":"A","explanation":"要计算这5天气温的平均值,首先将所有气温相加:(-2) + 0 + 3 + (-1) + 4 = 4。然后将总和除以天数5,得到平均值:4 ÷ 5 = 0.8。因此,这5天气温的平均值是0.8℃。本题考查有理数的加减运算以及数据的整理与描述中的平均数计算,属于简单难度。","options":[{"id":"A","content":"0.8℃"},{"id":"B","content":"1.0℃"},{"id":"C","content":"1.2℃"},{"id":"D","content":"1.4℃"}]},{"id":2462,"content":"如图,在平面直角坐标系中,点A的坐标为(0, 4),点B的坐标为(6, 0)。一次函数y = kx + b的图像经过点A和点B。点C是该函数图像上的一点,且横坐标为m(0 < m < 6)。以AC为边作等腰直角三角形ACD,使得∠ACD = 90°,且点D位于第一象限。连接BD。当△ABD为等腰三角形时,求所有可能的m值,并说明对应的点D的坐标。","type":"解答题","subject":"数学","grade":"八年级","stage":"初中","difficulty":"中等","answer":"待完善","explanation":"解析待完善","options":[]},{"id":147,"content":"小明用一根长为20厘米的铁丝围成一个长方形,他发现当长方形的长和宽都是整数厘米时,面积会随着长和宽的变化而变化。在所有可能的长和宽组合中,面积最大的长方形的面积是多少平方厘米?","type":"选择题","subject":"数学","grade":"初一","stage":"初中","difficulty":"简单","answer":"C","explanation":"长方形的周长为20厘米,因此长 + 宽 = 10厘米。当长和宽都是整数时,可能的组合有:(1,9)、(2,8)、(3,7)、(4,6)、(5,5)等。对应的面积分别为:9、16、21、24、25平方厘米。其中当长和宽都是5厘米时,面积最大,为25平方厘米,此时长方形为正方形。因此正确答案是C。","options":[{"id":"A","content":"20"},{"id":"B","content":"24"},{"id":"C","content":"25"},{"id":"D","content":"30"}]}]