美国初中数学竞赛mathcounts
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amc10难度相当于几年级
amc10相当于国内数学8年级--10年级的水平。
AMC系列的全称”American Mathematics Competitions “,它是由美国数学协会举办的,是美国最老的(1950年开始举办)的和最负盛名的初高中生数学竞赛。
AMC10的受众群体是针对10年级及以下,8年级及以上的学生(对部分AMC8成绩优异的学生也可以参加)开办的数学知识竞赛。
它的题型为25道选择题,总时长为75分钟,总分150分,答对加6分,答错不扣分,不答得1.5分。
amc比赛的规定
是由美国数学协会于1950年正式成立的。
试题由简单到难,一点点的让学生感觉到具有挑战性,可以让所有喜欢数学或者是热爱数学的学生都能参与其中。
同时,在这个过程中也可以让学生感受到某种挑战。
目前amc是世界上可信度和效度最高的一个数学比赛,普及程度非常广,在全球有近百个国家的孩子热衷于这个比赛,在各个国家甚至达到了几千所学校,会参与到这样的一个比赛当中。
在美国上千种各类数学比赛当中,它是唯一的国际数学奥林匹克国家队的选拔体系从最底层开始的是amc8,然后往上进阶到amc10、amc12,再往上到aime美国数学邀请赛,
再往上就是usamo和imo。
美国中学数学奥林匹克竞赛预选赛
美国中学数学奥林匹克竞赛预选赛(MATHCOUNTS Pre-Competition)是一项全国性的中学数学竞赛项目,旨在激发青少年对数学的兴趣,增强技能,培养团队精神。
学生们可以通过参加本次竞赛,提高他们的个人技能,触及更高的学术成就,并通过参加全国排名和多元化的比赛环节获取此次竞赛的经历。
竞赛的各个阶段是:1、学校级比赛:每年11月下旬,在美国的每一家学校都会举行小规模的数学测验,根据学生的成绩筛选出积极参与者晋级第二赛季;2、赛区级比赛:每年3月上旬,每一个美国各州都会举行赛区级比赛,根据学生的成绩筛选出来晋级第三赛季;3、全国级比赛:每年5月前后,美国联邦政府将要求美国各州举行全国级比赛,由赛区级比赛获胜者参加,最终形成全国排名。
美国中学数学奥林匹克竞赛预选赛的竞赛任务通常包括数学思维题,数学实践题以及应用题。
此外,学生也可以竞争参加奥林匹克竞赛单项竞赛,如趣味组和速算组等。
总体而言,参赛学生将有机会体验一种充满挑战与乐趣的数学竞赛。
aime 2021解析
AIME,即美国初级数学竞赛(American Invitational Mathematics Examination),是由美国数学协会(MAA)举办的一
项全国性数学竞赛。
该竞赛旨在挑战中学生的数学解决问题能力,
鼓励他们在数学领域展现出卓越的才能。
AIME竞赛是美国数学竞赛
体系中的一部分,通常由在AMC(American Mathematics Competitions)考试中表现突出的学生参加。
AIME竞赛的题目通常涉及代数、几何、概率和数论等数学领域,难度较高,需要考生具备扎实的数学基础和解决问题的能力。
竞赛
时间为3小时,共有15道选择题,每道题目都有一个唯一的正确答案。
考生需要在规定的时间内完成这些题目,并填写答案。
AIME竞赛对参与者的数学思维能力和解决问题的技巧提出了很
高的要求。
参加AIME竞赛不仅可以激发学生对数学的兴趣,还可以
锻炼他们的逻辑思维和数学推理能力。
此外,AIME竞赛的成绩也被
一些著名大学作为评定学生数学能力的重要参考。
总的来说,AIME竞赛作为美国数学竞赛体系中的重要组成部分,
对于提高学生的数学水平、培养他们的数学兴趣和解决问题的能力起着重要的作用。
希望我的回答能够对你有所帮助。
SCCS Math CurriculumSCCS Math curriculum is aimed to provide students with a supplement learning opportunity in Math. The classes are designed to strength student’s understanding of math concepts and to enhance their math skills. The teachers achieve the goal through review of the grade appropriate math contents and practice at the class. Additional practices will be assigned as homework.SCCS use Spectrum Math series for Math classes Grade 3 to 6. Developed by experts in the field of education, each title in the Spectrum workbook series offers grade-appropriate instruction and reinforcement in an effective sequence for learning success. At the beginning of each academic year, the teacher in each grade will have a pre-test to assess the students’ true math levels and may adjust each student’s grade level accordingly.SCCS offer three more Math classes – Pre-Algebra, Algebra and Math Count, for those students who are passionate about learning Math. Pre-Algebra is designed to prepare students for the study of algebra by reviewing and practicing the important math concepts and skills necessary for learning Algebra. Algebra is designed as equivalence to algebra I at regular schools. This class will be appropriate for students who are taking algebra I at schools and would like to improve their problem solving skills, or for students who have finished algebra I but want to review the concepts and prepare for more advanced math courses. Math Count will provide students with the guided practice of typical problems in Math Count Competition.In addition, SCCS collaborates with the Learning Consultants Group to offer PSAT Math and SAT Math test prep classes for those high school students who are preparing to take PSAT and SAT tests. These classes are taught by experts from the Learning Consultants Group. Past PSAT and SAT test questions are used for students’ to practice in the classes and the teachers will provide students with guidance of test strategies and with review of important relevant math concepts and knowledge.For more information of the contents of each SCCS Math courses, please click the hyperlinks below.Contents_of_SCCS_Math Grade 3Grade 4Grade 5Grade 6Pre-AlgebraAlgebraMath CountChapter 1-Adding and Subtracting 1 and 2 Digit Numbers (with renaming) Chapter 2-Numberation through 100,000Chapter 3- Adding and Subtracting 2 and 3 Digit Numbers (with renaming) Chapter 4- Adding and Subtraction to 4 Digits (with renaming)Chapter 5- Multiplying through 2 Digits by 1 DigitChapter 6- Division Facts through 81/9Chapter 7- FractionsChapter 8- Customary MeasurementChapter 9- Metric MeasurementChapter 10- Money, Time and CalendarChapter 11- Graphs and ProbabilityChapter 12- GeometryChapter 13- Preparing for AlgebraReturn to the topChapter 1- Adding and Subtracting 1 and 2 DigitsChapter 2- Numeration through 1,000,000Chapter 3- Adding and Subtracting 3 through 5 DigitsChapter 4- Multiplying through 3 Digits by 2 DigitsChapter 5- Division Facts through 81/9Chapter 6- Dividing 2 and 3 Digits by 1 DigitChapter 7- Fractions, Decimals, and MoneyChapter 8- Customary MeasurementChapter 9- Metric MeasurementChapter 10- Graphs and ProbabilityChapter 11- GeometryChapter 12- Preparing for AlgebraReturn to the topChapter 1-Adding and Subtracting through 6 DigitsChapter 2- Multiplying through 4 Digits by 3 DigitsChapter 3- Dividing through 5 Digits by 2 DigitsChapter 4- Understanding FractionsChapter 5- Adding FractionsChapter 6- Subtracting FractionsChapter 7- Multiplying FractionsChapter 8- Dividing FractionsChapter 9- Customary MeasurementChapter 10- Metric MeasurementChapter 11- Graphs and ProbabilityChapter 12- GeometryChapter 13- Preparing for AlgebraReturn to the topChapter 1- Adding and Subtracting through 6 DigitsChapter 2- Multiplying and Dividing Whole NumbersChapter 3- Understanding FractionsChapter 4- Adding and Subtracting FractionsChapter 5- Multiplying and Dividing FractionsChapter 6- Adding and Subtracting DecimalsChapter 7- Multiplying and Dividing DecimalsChapter 8- Finding PercentsChapter 9- Customary MeasurementChapter 10- Metric MeasurementChapter 11- Probability and StatisticsChapter 12- GeometryChapter 13- Preparing for AlgebraReturn to the topPre_AlgebraThis course is designed for students who enjoy math and who have completed an elementary school (grades 1-6) math curriculum. Pre-Algebra exposes students to a wide variety of mathematical topics taught from a problem solving perspective. Pre-Algebra includes a thorough exploration, review, and practice of the fundamentals of arithmetic, including fractions, exponents, and decimals. The teacher will introduce beginning topics in number theory and algebra, including common divisors and multiples, primes and prime factorizations, basic equations and inequalities, and ratios. The teacher may also include subjects from geometry, especially subjects that further understanding of algebra in applications to area and volume.Return to the topAlgebraIn this class, majority of the time will be devoted to problem solving rather than teaching new knowledge. The course will follow closely what students are learning at regular schools. In the beginning, a quick review of pre-algebra will be provided, and then the class will advance to algebra topics shown below.- Functions;- Linear equations;- Inequalities and linear inequalities;- Systems of linear equations;- System of linear inequalities- Exponential functions;- Quadratic functions.Return to the topMath_CountMath counts class is prepared for students attending 7th and 8th grade. This course covers arithmetic, mathematics, algebra, and geometry (some contents may be beyond the middle school level). The student will use this knowledge to solve complex word problems. During the first semester, each of these subjects will be reviewed, and during the second semester, past Math counts competition tests will be used as the teaching material for practice (homework) and illustration (in-class).Return to the top数学课程我校数学课程教学的目标在于激发学生对数学的兴趣, 并提高学生分析和解决数学问题的能力。
1. Read each problem carefully and multiple timesI cannot stress this point enough. This is the single most important part of MATHCOUNTS for a great number of students, myself included. Misreading the problem is likely one of the leading causes, if not the leading cause, of incorrect answers. Personally, I would have made Nationals in 7th grade had I read some key words correct ("smallest" instead of "largest", "first" instead of "last", etc.). I also would likely have made National CD had I managed to read "Positive" on the final Target question.2. Manage your timeThis falls second on the list of importance, just below misreading. Note that poor time management will likely hamper your ability to read carefully (and multiple times), which will likely lead to even more time wasted. Know when to "give up" on a problem in favor of easier questions. They're all worth the same.3. Do all the questionsDifficulty is extremely difficult to gauge (heh) in general, but even more so when the problems are all roughly the same difficulty level. Don't be intimidated by the question number - many times a #26 will be a giveaway question, while #14 will be one of the more difficult problems. You should aim to at least read through all of the questions (carefully!) and to make a serious attempt on most of them.4. Organize your workIn MATHCOUNTS, you will likely spend a lot of time checking your answers, something that will be much harder to do if your paper is messy and disorganized. The method that you choose will be up to you, but my recommended method is to either section off your paper before the test begins, or to section off your paper as you complete problems. Write down all non-trivial steps - you'll use these for reference. You should include computation, either to the side or in the problem, as this is where you'll do most of your checking.5. Do problems multiple waysMost problems will have several valid approaches to the answer. In most cases, one approach will immediately jump out to you, and you will follow it to the answer. A great way to check your answer is to do the problem in another way, even if it's just slightly different. For example, if you do 5(3+5) as 5*3+5*5 and 5*8, you'll be significantly less likely to make a computation error. Similarly, if use similar triangles and Power of a Point, getting the same answer, you can bereasonably sure your answer is correct (but if they're different, time to find out why!). When using a second method, you shouldn't know what answer you're trying to achieve - you may consciously or subconsciously force yourself to get that answer.6. Make assumptionsThis is a very dangerous, but potentially rewarding technique. Mostly used for time-saving (and especially in CD), what looks like it's true usually is. Rely on your intuition - it's usually a very powerful tool. A combination of practice and experience gives you an intuition that can easily outweigh the time needed for a rigorous solution. This isn't to say guess; rather to make educated guesses.For example, take 2011 Chapter Target #8. From experience, I was able to immediately guess that the b in was 2 ( is highly associated with 45-degree angles and squares), which immediately led to (there's no other possible answer that makes it between 0 and 1). This gives the correct answer of 3 without any effort, on a relatively difficult problem (for chapter).Disclaimer: Only use this technique when necessary. If you have time, focus on checking problems you used this method on FIRST, before checking others.7. Don't check in orderIt's usually a waste of time to check from #1 to #30 in that order. You'll end up using your precious time checking problems that are almost certainly correct instead of checking those that need it. Make a mark on your paper next to the question number signifying that you are unsure of your answer. Make a seperate mark if you arrived at the answer without a rigorous solution (see tip 6). Focus on checking these first. After that, focus on checking problems that you aren't 100% sure of, then go to the easier problems. I also made notes of problems that were essentially just computation, because I always made computational errors on early problems. You may decide that you need marks for certain issues that you typically encounter, which is also fine.8. CD - Buzz in before you know the answerAnother dangerous but rewarding technique, only do so if you know you can get the answer within 3 seconds. For example, if you know that the answer is 15*16, that would be a good time to buzz in. Countdown is also an important time to utilize tip 6 - use your intution! With only 45 second per problem, and the "race" element, you need to be very fast in order to pick up your points. For example, this question: If , compute n, from the 2011 State CDround, was one that I instantly recognized as a question I could solve within 3 seconds (btw, so did my opponent). I instantly buzzed in (before I knew the answer!), gave the correct answer of 5, and ended up winning my next match to make Nationals. Had I not buzzed in when I did, my opponent would have (he was going for his buzzer as well), and I would have missed out. In this case, the extra few milliseconds were incredibly important.9. Take it easyFinally, don't dwell on your results, good or bad, however cliche that sounds. Poor results do not really indicate much in a competition like MATHCOUNTS, where the difference between a national winner and a person just missing out on State CD is generally very small. It comes down to tiny speed tricks that makes one person just a little bit faster than the other guy, which can be enough. I know it won't feel like it at the time, but you're the lucky ones. As middle schoolers, you have so much time left to improve, both math-wise and competition-wise (yes, they can be seperate things). If you get 11th written at State (which I did in 7th grade), or 5th CD (which my friend did last year at States [because I beat him]), you'll be originally crushed, but in the end, it really makes so little difference. Both me and my friend do decently at math now, despite our... failures at MATHCOUNTS. There's a lot more to life than it.第1条:仔细、多次读题这点再怎么强调也不过分这是MATHCOUNTS最重要的一条技巧,不仅对学生,也包括我自己。
美国中学生的奥数路作者:文/Cathy来源:《出国》 2016年第6期文/Cathy美国中小学生参加数学竞赛的不多,但在历年世界奥数竞赛中的成绩,美国队仅次于中国队。
美国奥数队的6名成员是通过一个金字塔形的竞赛体系决定的。
每年,American Mathematics Competitions (AMC),美洲数学竞赛,从低到高,逐层选拔人才。
AMC8是面向8及以下年级的竞赛。
竞赛时间40分钟,25道选择题。
每道题1分,总分25分,做错不倒扣分。
每年11月的一个周二比赛。
AMC10是面向10及以下年级的比赛。
竞赛时间75分钟,25道选择题。
答对一道题得6分,没有回答的题得1.5分,答错不得分,总分是150分。
每年有两次比赛,AMC10A在2月份的第一个周二,AMC10B晚15天。
学生可以参加任何一个,也可以A,B都参加,取最好成绩。
AMC12是面向12及以下年级的比赛。
规定跟AMC10一样,甚至有部分考题都一样,只是比AMC10稍微难一些。
考试时间跟AMC10在同一天。
为了获得更多晋级机会,学生可以选择参加两个考试,比如AMC10A和AMC12B。
只有在AMC10或AMC12中取得好成绩的学生,才能被邀请参加American Invitational Mathematics Examination (AIME)美洲数学邀请赛好成绩的标准是,在AMC10中,分数最高的2.5%的学生。
在AMC12中,分数最高的5%的学生。
美洲数学邀请赛AIME的难度大增,有些题目超越了高中教学范畴。
想在AIME得高分,需要特殊的培训。
竞赛时间3个小时,做15道题。
答对得1分,做错或空白不得分,总分15分。
近几年的AIME平均分只有5分左右,每年也有满分的学生。
AIME每年在3月份举行两次,但学生只能参加其中一次竞赛。
再高一级的比赛是,United States of America Mathematical Olympiad(USAMO),美国数学奥林匹克竞赛。
amc知识点公式摘要:一、前言二、AMC知识点简介1.数论2.代数3.几何4.组合三、AMC公式汇总1.数论公式2.代数公式3.几何公式4.组合公式四、AMC知识点与公式应用实例1.数论应用实例2.代数应用实例3.几何应用实例4.组合应用实例五、结论正文:一、前言AMC(American Mathematics Competitions)是美国数学竞赛的缩写,旨在激发学生对数学的兴趣,发现和选拔数学人才。
竞赛涉及的知识点广泛,包括数论、代数、几何和组合等。
为了更好地应对AMC竞赛,了解相关知识点和公式是至关重要的。
二、AMC知识点简介1.数论数论是研究整数性质的数学分支,包括素数、同余、最大公约数和最小公倍数等概念。
2.代数代数是研究数和数之间的关系和运算的数学分支,包括线性方程、二次方程、函数和图像等。
3.几何几何是研究空间中形状和位置关系的数学分支,包括点、线、面的性质,以及圆、三角形、四边形等特定形状的性质。
4.组合组合是研究有限集合中元素排列和组合的数学分支,包括计数原理、排列组合和二项式定理等。
三、AMC公式汇总1.数论公式π(x) = (x / (1 - 1/3 + 1/5 - 1/7 + ...)) * (1 + 1/(1 - 1/2))其中,π(x)表示小于等于x的素数个数。
2.代数公式对于二次方程ax^2 + bx + c = 0,它的解为:x1,2 = (-b ± √(b^2 - 4ac)) / (2a)3.几何公式勾股定理:a^2 + b^2 = c^2其中,a、b为直角三角形的两条直角边,c为斜边。
4.组合公式组合数:C(n, m) = n! / (m! * (n - m)!)其中,n表示元素总数,m表示选取元素的数量。
四、AMC知识点与公式应用实例1.数论应用实例在求解素数问题时,可以利用π(x)公式估算小于等于x的素数个数。
2.代数应用实例在解决二次方程问题时,可以利用二次方程求根公式求解。
奥巴马接见了美国初中数学竞赛团体冠军知鸣介绍:这是2012年11月21日左右的新闻,这起新闻特别在于这6名冠军当中,有4名是华裔,这无疑勾起了不少华人的心。
新闻内容:美国有多项教育调研显示,亚裔中小学学生的阅读和数学成绩普遍高于白人、拉丁裔和非裔等其他族裔学生。
因此,弗吉尼亚州教育委员会最近在为后进中小学制定2012-2013学年度教学成果目标时,决定将族裔因素纳入考虑范围——为各族裔学生制定不同的及格率标准。
此举招致不少非议,被指涉嫌种族歧视。
最近,一张美国总统奥巴马接见美国初中数学竞赛团体冠军的照片在网上流传甚广。
从照片上看,6名学生中有4张华裔面孔,于是有网友调侃:奥巴马接见的大概是中国初中数学竞赛团体冠军吧。
这张照片摄于2010年6月,获奖学生参加的比赛叫MATHCOUNTS,是美国一年一度的有30年历史的中学数学竞赛。
近年来,这项比赛有被亚裔学生“垄断”的趋势。
比如,今年5月决出的新一届获奖者,个人比赛前4名都是亚裔,其中3人是华裔。
不同肤色不同标准美国弗吉尼亚州教育委员会10月发布新版标准,对不同族裔学生设置了不同的及格率要求。
根据该标准,在2012-2013学年,弗吉尼亚州后进中小学的阅读和数学两科教学“合格”标准分别为:亚裔学生及格率92%和82%,白人学生90%和68%,拉丁裔学生80%和52%,非裔学生76%和45%。
此外,“经济困难学生”、“英语程度有限学生”和“残疾学生”等群体也有相应指标。
弗吉尼亚州教育官员帕翠西·赖特近日接受美国全国公共广播(NPR)采访时说,弗吉尼亚当然期待所有的孩子都能在考试中答出同样多的问题,但现实是拉丁裔和非裔学生确实在考试成绩上与白人和亚裔学生有差距,制定新标准是为了帮助后进学生获得更多进步的时间。
根据这份标准中的分阶段期望,到2017-2018学年,所有群体的平均及格率有望达到73%,这些后进学校和州内成绩较好学校之间的差距将大大缩小。
amc数学竞赛规则AMC数学竞赛规则AMC数学竞赛(American Mathematics Competition)是美国数学竞赛系统中的一项重要竞赛,旨在选拔出具有数学天赋和潜力的学生,并为他们提供展示才华和进一步发展数学能力的机会。
下面将介绍AMC数学竞赛的规则和相关注意事项。
一、竞赛形式AMC数学竞赛分为三个级别:AMC 8、AMC 10和AMC 12。
AMC 8适用于六年级至八年级的学生,AMC 10适用于高中一年级至高中二年级的学生,AMC 12适用于高中一年级至高中三年级的学生。
每个级别的竞赛都由一套选择题组成,包括25道题目,答题时间限制为75分钟。
二、竞赛内容AMC数学竞赛的题目内容涵盖了各个数学领域,包括代数、几何、数论、概率与统计等。
题目难度逐渐增加,旨在考察学生的数学思维能力、问题解决能力和创新能力。
竞赛中的每道题目都有五个选项,选手需要选择正确答案并填涂在答题卡上。
三、竞赛时间和地点AMC数学竞赛通常在11月至2月期间进行,具体时间和地点由各个学校或数学协会决定。
学校可以申请成为AMC数学竞赛的考点,并组织学生参加竞赛。
竞赛的时间一般为晚上或周末,以便更多学生能够参与。
四、竞赛分数和奖项竞赛结束后,学生的答题卡将被收集并送往美国数学协会进行批阅。
根据学生的得分,将评选出优秀学生并颁发不同级别的奖项,如:AMC奖状、AMC成绩证明和AMC证书等。
同时,高分者还有机会晋级到更高级别的数学竞赛,如AIME(美国初级数学选拔赛)和USAMO(美国数学奥林匹克)等。
五、竞赛准备和参与建议1. 提前准备:参加AMC数学竞赛需要提前进行充分的数学知识和解题技巧的准备。
可以参加数学辅导班、阅读相关的数学书籍和参考资料,积累解题经验。
2. 制定学习计划:制定合理的学习计划,合理安排复习时间,分配时间进行各个数学领域的学习和练习。
3. 解题技巧:熟悉各种不同类型的数学题目,掌握解题技巧和方法。
美国中学生的数学达人竞赛作者:张森凤整理来源:《华人时刊》2012年第07期数学数学,应该很少有小孩喜欢,尤其是女孩,通常敬而远之。
大女儿从小口齿伶俐,中英文都在旁听大人谈话中了悟,不学自通,可是数学这门课,唉,实在不行。
人各有长,对于大女儿的数学,我也就不寄予厚望,直到她上了中学。
首先是被分到资优班,这没什么,美国小孩的数学都差,九九乘法背不起来,手指脚趾齐用的人比比皆是。
大女儿能进数学资优班,大概是因为我特别买数学练习本给她在家练习的成果。
别想说这是多难的练习喔,是在超市买的,给小学不同年级的练习本,有很多彩色图片,每页大约十题的练习,而且由于学校很少布置家庭作业,我又不知道进度,只能从头让女儿做,一天一页,不懂的再教。
参加数学社团大概是女儿开窍了吧,很令人惊讶地,六年级升七年级时,她居然通过前代数测验,直接上相当于九年级的高中代数,接下来又上高中几何,这学期还突然抱回一个数学之星的奖!然后某天,她跟我说,想参加课后一个数学俱乐部,Mathcounts club。
“参加这个社团多久要去一次啊?”我很怕开车,每个星期开车去买一次菜就很烦了,如果两个女儿各参加一个要留校的活动,就得开三次车!这是我的极限!“老师没说,但是大概一个月一次。
”这个数学社团在做什么呢?难道就是几个小孩一起讨论数学题目吗?怎么有人要参加啊?第一次活动结束后,我问:“好玩吗?有几个人去啊?”“还好啦,只有五个人,但是老师说会有数学比赛喔!我们会代表学校参加比赛!只是题目好难,我会做的没几题,每一题都要花好多时间。
”女儿真是变成比赛狂了!一听到比赛眼睛就亮起来!“真的啊?我看看。
”我不讨厌数学,也不太怕数学,可是一看……哇,是我早已忘光的三角函数!好难喔!“没关系啦,反正是课外活动。
”我不太觉得数学是女儿的专长,愿意多花时间就已经让我很偷笑了!所以接下来有几次的活动改成星期五放学后,我都没让女儿去,因为那是去前夫家的日子。
全郡数学竞赛就这样混了几个月,断断续续总共做了三四次练习,老师发了一张通知单,上面有比赛日期,是在星期六,而且说,每个学校只能有一个正式代表队,总共四名成员,多出来的学生就只能算是非正式代表,不计分,也就是说,参加好玩的啦!我问女儿:“你想去吗?”“我不知道,是在星期六,而且有个人赛,还是限时答题!我不是速算型的人,我喜欢有充分时间慢慢想。
MATH COUNTS® Problem of the Week Archive It All Adds to Ten – August 2, 2010
Problems
Thank you to Tom Butts for contributing this week's set of problems!!
Today’s date is 8/2/10 – a date where the sum of the month and the day equals the number formed by the last two digits of the year. How many such dates are there in 2010?
How many ordered sets of three positive integers have a sum of 10? Note: The set 8, 1, 1 is different from the set 1, 8, 1.
How many ordered sets of positive integers with two or more elements have a sum of 10? Solutions
1/9, 2/8, 3/7, 4/6, 5/5, 6/4, 7/3, 8/2, 9/1
So, 9 is our answer.
This one can be solved by making an organized list, as follows:
# of possible arrangements
x1 x2 x3
8 1 1 3
7 2 1 6
6 3 1 6
6 2 2 3
5 4 1 6
5 3 2 6
4 4 2 3
4 3 3 3
Total poss. ordered sets = 36
Another way to solve this would be by thinking of a row of ten 1s
1_1_1_1_1_1_1_1_1_1
Each possible arrangement corresponds to inserting a “+” sign in two of the nine “_” between the 1s. For example 1_1 + 1_1_1_1_1 + 1_1_1 corresponds to the arrangement 2 + 5 + 3 = 10. Thus there are 9 choose 2 ways to choose the two spaces, which is 36.
Problem 1 shows there are 9 choose 1 (9C1) sets of two positive integers whose sum is 10. Problem 2 shows there are 9C2 sets of three positive integers whose sum is 10. Generalizing the secondary solution method for problem 2, there are 9 choose 3 sets of 4
positive integers whose sum is 10. Continuing, the total number of sets of positive numbers whose sum is 10 is 9C1 + 9C2 +… + 9C9 = 29 – 1 = 511。