世界數(shù)學(xué)奧林匹克經(jīng)典：概率與期望

　　Probability theory is an important branch of mathematics， with wide applications in many fields. It is not only a required course for students of science and technology at universities， but also has entered into Chinese high school textbooks now.This little book will， in an interesting problem-solving way， explain what probability theory is： its concepts， methods and meanings; particularly， two important concepts-probability and mathematical expectation （briefly expectation）-are emphasized. It consists of 65 problems， appended by 107 exercises and their answers.As an extracurricular book providing supplement materials to and advanced knowledge beyond high school textbooks， its aim is to stimulate study interests of students and broaden their knowledge horizons. Some problems were given a little deeper treatment， which can be used as topics for explorative study; and they can also be skipped temporarily if a reader feels difficult to understand them at the beginning.It is presupposed that our readers possess a knowledge of permutations and combinations， and it would be better if they have already learned basic probability theory from their textbooks. However， in order to avoid repetition， we mention as little as possible the contents of textbooks.It is a random event that this little book reaches you. I do not know how much the probability that this event occurs is. However， it is my expectation that this book could reach you， which means that you have a special affinity with it.

　　作者簡(jiǎn)介單墫，我國(guó)著名數(shù)學(xué)家、數(shù)學(xué)教育家。1943年11月生，1964年揚(yáng)州師范學(xué)院數(shù)學(xué)系畢業(yè)，1983年在中國(guó)科學(xué)技術(shù)大學(xué)獲理學(xué)博士學(xué)位，師從王元院士，為我國(guó)首批獲得理科博士學(xué)位的18人之一。博士畢業(yè)后在南京師范大學(xué)任教，1991年被評(píng)為全國(guó)優(yōu)秀教師并享受?chē)?guó)務(wù)院特殊津貼，1992年被授予有突出貢獻(xiàn)的中青年專(zhuān)家稱(chēng)號(hào)。曾任南京數(shù)學(xué)學(xué)會(huì)理事長(zhǎng)，南京師范大學(xué)數(shù)學(xué)系主任，中國(guó)數(shù)學(xué)奧林匹克委員會(huì)委員、教練組組長(zhǎng)，國(guó)家教育司門(mén)理科試驗(yàn)班專(zhuān)家組組長(zhǎng)。單墫教授在數(shù)學(xué)領(lǐng)域的初等數(shù)論、解析數(shù)論和組合數(shù)學(xué)研究方面取得了一些國(guó)際先進(jìn)水平的成果。他還在數(shù)學(xué)普及與數(shù)學(xué)競(jìng)賽方面，傾注了大量的時(shí)間和精力。作為領(lǐng)隊(duì)和主教練，多次率領(lǐng)中國(guó)國(guó)家隊(duì)參加國(guó)際數(shù)學(xué)奧林匹克（IMO）均獲全球總分，為我國(guó)數(shù)學(xué)教育事業(yè)作出重大貢獻(xiàn)。