华图名师模块1班数学运算讲义李委明2.docx
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华图名师模块1班数学运算讲义李委明2
名师模块班讲义
数学
运算
主讲：
李委明
目录
第一课时：
代入排除法.....................................................................................................5
课前热身..............................................................................................................................5
要点评述..........................................................................................................................5
例题精析.............................................................................................................................5
课后巩固............................................................................................................................6
第二课时：
强化训练一................................................................................................8
第三课时：
方程解题思想..................................................................................................10
课前热身...............................................................................................................................10
要点评述...............................................................................................................................10
例题精析..............................................................................................................................10
课后巩固...............................................................................................................................12
第四课时：
强化训练二........................................................................................................13
第五课时：
数列与平均数....................................................................................................15
课前热身...............................................................................................................................15要点要点评述...............................................................................................................................15
例题精析...............................................................................................................................15
课后巩固............................................................................................................................16
第六课时：
强化训三..........................................................................................................17
第七课时：
容斥原理.............................................................................................................18
课前热身..............................................................................................................................18
要点评述..............................................................................................................................18
例题精析..............................................................................................................................18
课后巩固................................................................................................................................20
第八课时：
强化训练四........................................................................................................22
第九课时：
行程问题................................................................................................................24
课前热身................................................................................................................................24
要点评述.......................................................................................................................24
例题精析..............................................................................................................................24
课后巩固.........................................................................................................................25
第十课时：
强化训练五.......................................................................................................26
第十一课时：
排列组合........................................................................................................28
课前热身.............................................................................................................................28
要点评述...........................................................................................................................28
例题精析..............................................................................................................................28
课后巩固............................................。
.................................................................................28
第十二课时：
强化训练六.................................................................................................31
第十三课时：
十字交叉法..................................................................................................33
课前热身..........................................................................................................................33
要点评述..........................................................................................................................33
例题精析............................................................................................................................33
课后巩固............................................................................................................................34
第十四课时：
调和平均数
课前热身......................................................................................................................................35
要点评述............................................................................................................................35
例题精析..........................................................................................................................36
课后巩固.......................................................................................................................37
第十五课时：
转化归一法
课前热身.............................................................................................................................39
要点评述............................................................................................................................39
例题精析.............................................................................................................................39
课后巩固..........................................................................................................................41
第十六课时：
几何问题
课前热身..................................................................................................................42
要点评述...........................................................................................................................42
例题精析....................................................................................................................42
课后巩固...................................................................................................................44
第十七课时：
浓度问题
课前热身............................................................................................................................46
要点评述..........................................................................................................................46
例题精析..................................................................................................................46
课后巩固.........................................................................................................................47
第十八课时：
牛吃草问题
课前热身........................................................................................................................48
要点评述.......................................................................................................................48
例题精析.....................................................................................................................48
课后巩固........................................................................................................................50
第十九课时：
边端问题
课前热身.....................................................................................................................51
要点评述.........................................................................................................................51
例题精析......................................................................................................................51
课后巩固.........................................................................................................................53
第二十课时：
年龄问题
课前热身.........................................................................................................................54
要点评述.....................................................................................................................54
例题精析.................................................................................54
课后巩固......................................................................................................................55
数学基础知识附录..............................................................................................56
数学运算讲义详细答案.........................................................................................61
【习题1】（内蒙古2008-14）某校人数是一个三位数，平均每班36人，若将全校人数的百位数与十位数对调，则全校人数比实际少180人，那么原校人数最多可以达到多少人？
A．900B．936C．972D．990
【习题2】（北京社招2009-15）某生产车间有若干名工人，按每四个人一组分多一个人,按每五个人一组分也多一个，按每六个人一组分还是多一个，该车间至少有多少名工人？
A.31B.41C.61D.122
【习题3】（安徽2008-7）一个袋子里放着各种颜色的小球，其中红色球占
1/4，后来又往袋子里放了10个红球，这时红球占总数的2/3，问原来袋子里有多少个球（）
A.8B.12C.16D.20
.要点评述
.“代入排除法”是数学运算题型当中最重要的技巧，这种方法结合题干与选项双向判断，是处
理行测“客观单选题”最为行之有效的方法。
.
“代入排除法”广泛运用在多位数问题、不定方程（组）问题、同余问题、和差倍比问题、年
龄问题、行程问题、周期问题等等题型。
.
“代入排除法”还可以利用数字的基本特性来完成，这就要求广大考生掌握基本的数字特性，
特别是对倍数的判断。
.
例题精析
【例1】（山西路警2010-11）甲、乙两数的和是305.8，乙的小数点向右移动一位就等于甲，则甲等于：
A.301B.297C.278D.264
【例2】（江西2009-45）某次考试中，小林的准考证号码是个三位数，个位数字是十位数字的2倍，十位数字是百位数字的4倍，三个数字的和是13，则准考证号码是（）。
A.148B.418C.841D.814
【例3】（北京2009-13）有一个两位数，如果把数码1，加在它的前面，那么可以得到一个三位数，如果把1加在它的后面，那么也可以得
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