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___。
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要找出这组数据的中位数,首先需要将数据按从小到大的顺序排列:3,4,5,6,7。由于数据个数为5(奇数个),中位数就是正中间的那个数,即第3个数。因此,中位数是5。选项C正确。
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[{"id":249,"content":"某学生用一根长为48厘米的铁丝围成一个长方形,若长方形的长比宽多6厘米,则这个长方形的面积是___平方厘米。","type":"填空题","subject":"数学","grade":"初一","stage":"小学","difficulty":"中等","answer":"135","explanation":"设长方形的宽为x厘米,则长为(x + 6)厘米。根据长方形周长公式:周长 = 2 × (长 + 宽),可得方程:2 × (x + x + 6) = 48。化简得:2 × (2x + 6) = 48,即4x + 12 = 48。解得4x = 36,x = 9。因此宽为9厘米,长为15厘米。面积为长 × 宽 = 15 × 9 = 135平方厘米。","options":[]},{"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":2355,"content":"如图,在平面直角坐标系中,一次函数 y = kx + b 的图像经过点 A(2, 5) 和点 B(−1, −1)。若点 C(m, n) 也在此函数图像上,且满足 m² − 4m + 4 + |n − 5| = 0,则点 C 的坐标为( )。","type":"选择题","subject":"数学","grade":"八年级","stage":"初中","difficulty":"中等","answer":"B","explanation":"首先,利用点 A(2, 5) 和点 B(−1, −1) 求一次函数的解析式。由斜率公式得:k = (5 − (−1)) \/ (2 − (−1)) = 6 \/ 3 = 2。将 k = 2 和点 A(2, 5) 代入 y = kx + b,得 5 = 2×2 + b,解得 b = 1。因此函数解析式为 y = 2x + 1。接着分析条件 m² − 4m + 4 + |n − 5| = 0。注意到 m² − 4m + 4 = (m − 2)²,所以原式可化为 (m − 2)² + |n − 5| = 0。由于平方项和绝对值均为非负数,两者之和为 0 当且仅当每一项都为 0,故有 m − 2 = 0 且 n − 5 = 0,即 m = 2,n = 5。因此点 C 的坐标为 (2, 5),对应选项 B。验证该点是否在函数图像上:当 x = 2 时,y = 2×2 + 1 = 5,符合。故正确答案为 B。","options":[{"id":"A","content":"(0, 1)"},{"id":"B","content":"(2, 5)"},{"id":"C","content":"(4, 9)"},{"id":"D","content":"(1, 3)"}]},{"id":2202,"content":"某学生在一次数学测验中记录了五次测验成绩与班级平均分的差值,分别为:+5,-3,+2,-1,+4。这五次成绩中,高于班级平均分的有几次?","type":"选择题","subject":"数学","grade":"七年级","stage":"初中","difficulty":"简单","answer":"B","explanation":"正数表示高于班级平均分,负数表示低于平均分。记录中的+5、+2、+4是正数,共3次高于平均分,因此正确答案是B。","options":[{"id":"A","content":"2次"},{"id":"B","content":"3次"},{"id":"C","content":"4次"},{"id":"D","content":"5次"}]},{"id":1906,"content":"某班级组织了一次环保知识竞赛,参赛学生需完成一份包含10道选择题的试卷。每答对一题得5分,答错或不答扣2分。一名学生最终得分为29分,请问这名学生答对了多少道题?","type":"选择题","subject":"数学","grade":"七年级","stage":"初中","difficulty":"简单","answer":"B","explanation":"设这名学生答对了x道题,则答错或不答的题目数为(10 - x)道。根据得分规则:每答对一题得5分,答错或不答扣2分,总得分为29分,可列出一元一次方程:5x - 2(10 - x) = 29。展开并化简:5x - 20 + 2x = 29 → 7x = 49 → x = 7。因此,这名学生答对了7道题。验证:7×5 = 35分,答错3题扣3×2 = 6分,35 - 6 = 29分,符合题意。","options":[{"id":"A","content":"6道"},{"id":"B","content":"7道"},{"id":"C","content":"8道"},{"id":"D","content":"9道"}]},{"id":2147,"content":"某学生在解方程时,将方程 2x + 3 = 7 的两边同时减去3,得到 2x = 4,然后两边同时除以2,得到 x = 2。这一过程主要运用了等式的哪一条基本性质?","type":"选择题","subject":"数学","grade":"七年级","stage":"初中","difficulty":"简单","answer":"D","explanation":"该学生在解题过程中,先两边同时减去3(运用了等式性质1:两边同时减去同一个数,等式仍成立),再两边同时除以2(运用了等式性质2:两边同时除以同一个不为零的数,等式仍成立)。因此,整个过程中综合运用了等式的基本性质,选项D最全面准确。","options":[{"id":"A","content":"等式两边同时加上同一个数,等式仍然成立"},{"id":"B","content":"等式两边同时减去同一个数,等式仍然成立"},{"id":"C","content":"等式两边同时乘或除以同一个不为零的数,等式仍然成立"},{"id":"D","content":"以上三条性质都运用了"}]},{"id":675,"content":"某学生测量了一个矩形花坛的长和宽,发现长比宽多2米。若花坛的周长为20米,则花坛的宽是___米。","type":"填空题","subject":"数学","grade":"初一","stage":"初中","difficulty":"简单","answer":"4","explanation":"设花坛的宽为x米,则长为(x + 2)米。根据矩形周长公式:周长 = 2 × (长 + 宽),代入得:2 × (x + x + 2) = 20。化简得:2 × (2x + 2) = 20,即4x + 4 = 20。解这个一元一次方程:4x = 16,x = 4。因此,花坛的宽是4米。","options":[]},{"id":635,"content":"某班级组织学生参加植树活动,男生每人种3棵树,女生每人种2棵树,全班共种了70棵树。已知该班男生人数比女生多5人,那么这个班有多少名女生?","type":"选择题","subject":"数学","grade":"初一","stage":"初中","difficulty":"简单","answer":"B","explanation":"设女生人数为x人,则男生人数为(x + 5)人。根据题意,男生每人种3棵树,女生每人种2棵树,全班共种70棵树,可列方程:3(x + 5) + 2x = 70。展开得:3x + 15 + 2x = 70,合并同类项得:5x + 15 = 70。两边同时减去15:5x = 55。两边同时除以5:x = 11。因此,女生有11人。验证:男生为16人,种树3×16=48棵,女生种树2×11=22棵,总计48+22=70棵,符合题意。","options":[{"id":"A","content":"10"},{"id":"B","content":"11"},{"id":"C","content":"12"},{"id":"D","content":"13"}]},{"id":574,"content":"某学生在整理班级同学的课外阅读时间时,记录了5位同学一周内每天阅读的分钟数,分别为:25、30、35、40、45。如果这5位同学每天阅读时间都增加10分钟,那么他们新的平均阅读时间是多少分钟?","type":"选择题","subject":"数学","grade":"初一","stage":"初中","difficulty":"简单","answer":"C","explanation":"首先计算原始数据的平均阅读时间:(25 + 30 + 35 + 40 + 45) ÷ 5 = 175 ÷ 5 = 35(分钟)。每位同学的阅读时间都增加10分钟,相当于整体平均数也增加10分钟。因此新的平均阅读时间为:35 + 10 = 45(分钟)。本题考查数据的整理与描述中的平均数概念,属于简单难度,符合七年级数学课程要求。","options":[{"id":"A","content":"35"},{"id":"B","content":"40"},{"id":"C","content":"45"},{"id":"D","content":"50"}]},{"id":845,"content":"在一次班级大扫除中,某学生负责统计各小组收集的废旧纸张重量(单位:千克)。记录如下:第一组收集3.5千克,第二组收集4.2千克,第三组收集2.8千克,第四组收集5.1千克。若全班平均每组收集4千克,则第五组应收集___千克才能达到平均标准。","type":"填空题","subject":"数学","grade":"初一","stage":"初中","difficulty":"简单","answer":"4.4","explanation":"要使五组的平均重量为4千克,则总重量应为 5 × 4 = 20 千克。前四组共收集 3.5 + 4.2 + 2.8 + 5.1 = 15.6 千克。因此第五组需要收集 20 - 15.6 = 4.4 千克。本题考查数据的收集与整理中的平均数计算,属于简单难度的应用题。","options":[]}]