某校七年级组织学生参加数学实践活动,需将一批实验器材分装到若干个箱子中。若每箱装8件,则剩余12件无法装下;若每箱装10件,则最后一个箱子只装了6件,其余箱子恰好装满。已知箱子数量为整数,且器材总数不超过200件。求这批实验器材的总件数和使用的箱子数量。
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该学生将方程两边同时除以3,这是应用了等式的基本性质:等式两边同时除以同一个不为零的数,等式仍然成立。这是七年级代数部分的重要内容,用于简化方程求解过程。
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[{"id":779,"content":"在一次环保活动中,某班级学生收集废旧电池。已知第一天收集了12节,第二天收集的数量比第一天多5节,第三天收集的数量是第二天的2倍。那么这三天一共收集了___节废旧电池。","type":"填空题","subject":"数学","grade":"初一","stage":"初中","difficulty":"简单","answer":"63","explanation":"第一天收集了12节;第二天比第一天多5节,即12 + 5 = 17节;第三天是第二天的2倍,即17 × 2 = 34节。三天总共收集的数量为:12 + 17 + 34 = 63节。本题考查有理数的加减与乘法运算在实际问题中的应用,属于整式加减与有理数运算的综合简单应用。","options":[]},{"id":1965,"content":"某学生在研究自家花园中不同种类花卉的生长高度时,记录了5种花卉的平均高度(单位:厘米):18.4, 22.6, 19.8, 25.2, 21.0。为了更清晰地比较这些数据,该学生决定将这些高度数据四舍五入到最近的整数后,再计算新数据集的极差。请问四舍五入后的数据极差是多少?","type":"选择题","subject":"数学","grade":"七年级","stage":"初中","difficulty":"中等","answer":"B","explanation":"本题考查数据的收集、整理与描述中对数据的近似处理及极差的计算。首先将原始数据四舍五入到最近的整数:18.4 → 18,22.6 → 23,19.8 → 20,25.2 → 25,21.0 → 21。得到新数据集:18, 20, 21, 23, 25。极差是最大值与最小值之差,即25 - 18 = 7。因此,正确答案为B。","options":[{"id":"A","content":"6"},{"id":"B","content":"7"},{"id":"C","content":"8"},{"id":"D","content":"9"}]},{"id":396,"content":"90度","type":"选择题","subject":"数学","grade":"初一","stage":"小学","difficulty":"简单","answer":"答案待完善","explanation":"解析待完善","options":[]},{"id":1934,"content":"在平面直角坐标系中,点A(2, 3)、B(5, -1)、C(-1, -4)构成三角形ABC。若点D是线段AB的中点,点E在y轴上,且△CDE的面积为15,则点E的纵坐标为______。","type":"填空题","subject":"数学","grade":"七年级","stage":"初中","difficulty":"困难","answer":"6或-12","explanation":"先求D点坐标((2+5)\/2, (3+(-1))\/2) = (3.5, 1)。设E(0, y),利用向量法或坐标面积公式S = 1\/2|x₁(y₂−y₃)+x₂(y₃−y₁)+x₃(y₁−y₂)|,代入C、D、E坐标解得|y−1|=18,故y=6或−12。","options":[]},{"id":281,"content":"某学生在整理班级同学的课外阅读时间数据时,记录了5名同学每周的阅读时间(单位:小时)分别为:3,5,4,6,2。这5名同学每周平均阅读时间是多少小时?","type":"选择题","subject":"数学","grade":"初一","stage":"初中","difficulty":"简单","answer":"B","explanation":"要计算平均阅读时间,需将所有同学的阅读时间相加,再除以人数。计算过程为:(3 + 5 + 4 + 6 + 2) ÷ 5 = 20 ÷ 5 = 4。因此,平均阅读时间是4小时。本题考查的是数据的收集、整理与描述中的平均数计算,属于七年级数学基础知识点,难度简单。","options":[{"id":"A","content":"3"},{"id":"B","content":"4"},{"id":"C","content":"5"},{"id":"D","content":"6"}]},{"id":1094,"content":"在一次班级环保活动中,某学生收集废旧纸张的重量比另一名学生的3倍还多2千克。如果两人一共收集了26千克,那么这名学生自己收集了___千克。","type":"填空题","subject":"数学","grade":"七年级","stage":"小学","difficulty":"简单","answer":"20","explanation":"设这名学生收集的废旧纸张重量为x千克,则另一名学生收集的为(3x + 2)千克。根据题意,两人共收集26千克,可列方程:x + (3x + 2) = 26。化简得4x + 2 = 26,解得4x = 24,x = 6。但注意:题目中描述的是“某学生收集的重量比另一名学生的3倍还多2千克”,因此应设另一名学生为x千克,则该学生为(3x + 2)千克。于是方程为x + (3x + 2) = 26,解得4x = 24,x = 6,那么该学生收集了3×6 + 2 = 20千克。因此答案是20。","options":[]},{"id":756,"content":"某学生测量教室中一个长方形黑板的周长为360厘米,已知它的长是宽的2倍,那么这个黑板的宽是___厘米。","type":"填空题","subject":"数学","grade":"初一","stage":"初中","difficulty":"简单","answer":"60","explanation":"设黑板的宽为x厘米,则长为2x厘米。根据长方形周长公式:周长 = 2 × (长 + 宽),代入得:2 × (2x + x) = 360。化简得:2 × 3x = 360,即6x = 360。解得x = 60。因此,黑板的宽是60厘米。本题考查一元一次方程在实际问题中的应用,属于简单难度。","options":[]},{"id":327,"content":"某学生在平面直角坐标系中描出点 A(2, 3) 和点 B(5, 7),然后他计算了这两点之间的距离。请问他计算出的距离最接近下列哪个数值?","type":"选择题","subject":"数学","grade":"初一","stage":"初中","difficulty":"简单","answer":"B","explanation":"根据平面直角坐标系中两点间距离公式:若两点坐标为 (x₁, y₁) 和 (x₂, y₂),则距离为 √[(x₂ - x₁)² + (y₂ - y₁)²]。将点 A(2, 3) 和点 B(5, 7) 代入公式得:√[(5 - 2)² + (7 - 3)²] = √[3² + 4²] = √[9 + 16] = √25 = 5。因此,两点之间的距离为 5,最接近的选项是 B。","options":[{"id":"A","content":"4"},{"id":"B","content":"5"},{"id":"C","content":"6"},{"id":"D","content":"7"}]},{"id":620,"content":"72度","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":213,"content":"某学生计算一个数的相反数时,将原数 5 写成了 -5,那么他得到的结果与原数的正确相反数相比,相差____。","type":"填空题","subject":"数学","grade":"初一","stage":"初中","difficulty":"简单","answer":"10","explanation":"原数是 5,它的正确相反数是 -5。某学生误将原数当作 -5,计算其相反数得到 -(-5) = 5。正确结果是 -5,而学生得到的是 5,两者相差 5 - (-5) = 10。因此答案是 10。","options":[]}]