<ol><li style="margin:0px;font-size:17px;line-height:normal;color:#454545;"><span style="font-size:17pt;"></span><span style="font-size:17pt;">동전을</span><span style="font-size:17pt;"> </span><span style="font-size:17pt;">백번</span><span style="font-size:17pt;"> </span><span style="font-size:17pt;">던졌더니</span><span style="font-size:17pt;"> </span><span style="font-size:17pt;">앞면이</span><span style="font-size:17pt;"> 70</span><span style="font-size:17pt;">번</span><span style="font-size:17pt;"> </span><span style="font-size:17pt;">뒷면이</span><span style="font-size:17pt;"> 30</span><span style="font-size:17pt;">번</span><span style="font-size:17pt;"> </span><span style="font-size:17pt;">나왔다</span><span style="font-size:17pt;">. </span><span style="font-size:17pt;">동전을</span><span style="font-size:17pt;"> </span><span style="font-size:17pt;">계속해서</span><span style="font-size:17pt;"> </span><span style="font-size:17pt;">던질때</span><span style="font-size:17pt;"> </span><span style="font-size:17pt;">언젠가</span><span style="font-size:17pt;"> </span><span style="font-size:17pt;">앞면이</span><span style="font-size:17pt;"> </span><span style="font-size:17pt;">나오는</span><span style="font-size:17pt;"> </span><span style="font-size:17pt;">횟수가</span><span style="font-size:17pt;"> </span><span style="font-size:17pt;">뒷면이</span><span style="font-size:17pt;"> </span><span style="font-size:17pt;">나오는</span><span style="font-size:17pt;"> </span><span style="font-size:17pt;">횟수와</span><span style="font-size:17pt;"> </span><span style="font-size:17pt;">같아지는</span><span style="font-size:17pt;"> </span><span style="font-size:17pt;">순간이</span><span style="font-size:17pt;"> </span><span style="font-size:17pt;">올</span><span style="font-size:17pt;"> </span><span style="font-size:17pt;">확률은</span><span style="font-size:17pt;">? </span><span style="font-size:17pt;">답</span><span style="font-size:17pt;"> :1 </span></li></ol><p style="margin:0px;font-size:17px;line-height:normal;color:#454545;"><span style="font-size:17pt;">도박사의</span><span style="font-size:17pt;"> </span><span style="font-size:17pt;">오류와</span><span style="font-size:17pt;"> </span><span style="font-size:17pt;">혼동해서는</span><span style="font-size:17pt;"> </span><span style="font-size:17pt;">안</span><span style="font-size:17pt;"> </span><span style="font-size:17pt;">됩니다</span><span style="font-size:17pt;">. </span><span style="font-size:17pt;">도박사의</span><span style="font-size:17pt;"> </span><span style="font-size:17pt;">오류는</span><span style="font-size:17pt;"> 101</span><span style="font-size:17pt;">번째</span><span style="font-size:17pt;">(</span><span style="font-size:17pt;">혹은</span><span style="font-size:17pt;"> </span><span style="font-size:17pt;">앞으로</span><span style="font-size:17pt;"> 10</span><span style="font-size:17pt;">번을</span><span style="font-size:17pt;"> </span><span style="font-size:17pt;">더</span><span style="font-size:17pt;"> </span><span style="font-size:17pt;">던지는</span><span style="font-size:17pt;"> </span><span style="font-size:17pt;">상황</span><span style="font-size:17pt;"> </span><span style="font-size:17pt;">등</span><span style="font-size:17pt;"> </span><span style="font-size:17pt;">횟수가</span><span style="font-size:17pt;"> </span><span style="font-size:17pt;">미리</span><span style="font-size:17pt;"> </span><span style="font-size:17pt;">정해진</span><span style="font-size:17pt;"> </span><span style="font-size:17pt;">경우</span><span style="font-size:17pt;">) </span><span style="font-size:17pt;">던졌을</span><span style="font-size:17pt;"> </span><span style="font-size:17pt;">때</span><span style="font-size:17pt;"> </span><span style="font-size:17pt;">뒷면이</span><span style="font-size:17pt;"> </span><span style="font-size:17pt;">나올</span><span style="font-size:17pt;"> </span><span style="font-size:17pt;">확률이</span><span style="font-size:17pt;"> </span><span style="font-size:17pt;">더</span><span style="font-size:17pt;"> </span><span style="font-size:17pt;">높다고</span><span style="font-size:17pt;"> </span><span style="font-size:17pt;">생각하는</span><span style="font-size:17pt;"> </span><span style="font-size:17pt;">오류입니다</span><span style="font-size:17pt;">. </span><span style="font-size:17pt;">큰수의</span><span style="font-size:17pt;"> </span><span style="font-size:17pt;">법칙은</span><span style="font-size:17pt;"> </span><span style="font-size:17pt;">시행의</span><span style="font-size:17pt;"> </span><span style="font-size:17pt;">횟수가</span><span style="font-size:17pt;"> </span><span style="font-size:17pt;">무한대로</span><span style="font-size:17pt;"> </span><span style="font-size:17pt;">갈</span><span style="font-size:17pt;"> </span><span style="font-size:17pt;">때</span><span style="font-size:17pt;"> </span><span style="font-size:17pt;">앞면</span><span style="font-size:17pt;">/</span><span style="font-size:17pt;">뒷면</span><span style="font-size:17pt;"> </span><span style="font-size:17pt;">비율이</span><span style="font-size:17pt;"> 1</span><span style="font-size:17pt;">에</span><span style="font-size:17pt;"> </span><span style="font-size:17pt;">가까워진다는</span><span style="font-size:17pt;"> </span><span style="font-size:17pt;">것을</span><span style="font-size:17pt;"> </span><span style="font-size:17pt;">말해줍니다</span><span style="font-size:17pt;">. </span><span style="font-size:17pt;">큰수의</span><span style="font-size:17pt;"> </span><span style="font-size:17pt;">법칙만으로는</span><span style="font-size:17pt;"> </span><span style="font-size:17pt;">앞면</span><span style="font-size:17pt;">/</span><span style="font-size:17pt;">뒷면</span><span style="font-size:17pt;"> </span><span style="font-size:17pt;">비율이</span><span style="font-size:17pt;"> </span><span style="font-size:17pt;">정확하게</span><span style="font-size:17pt;"> 1</span><span style="font-size:17pt;">이</span><span style="font-size:17pt;"> </span><span style="font-size:17pt;">되는</span><span style="font-size:17pt;"> </span><span style="font-size:17pt;">순간이</span><span style="font-size:17pt;"> </span><span style="font-size:17pt;">온다는</span><span style="font-size:17pt;"> </span><span style="font-size:17pt;">것을</span><span style="font-size:17pt;"> </span><span style="font-size:17pt;">증명할</span><span style="font-size:17pt;"> </span><span style="font-size:17pt;">수는</span><span style="font-size:17pt;"> </span><span style="font-size:17pt;">없습니다</span><span style="font-size:17pt;">. Random walk </span><span style="font-size:17pt;">이론을</span><span style="font-size:17pt;"> </span><span style="font-size:17pt;">적용하면</span><span style="font-size:17pt;"> </span><span style="font-size:17pt;">비율이</span><span style="font-size:17pt;"> 1</span><span style="font-size:17pt;">이</span><span style="font-size:17pt;"> </span><span style="font-size:17pt;">되는</span><span style="font-size:17pt;"> </span><span style="font-size:17pt;">순간이</span><span style="font-size:17pt;"> </span><span style="font-size:17pt;">반드시</span><span style="font-size:17pt;"> </span><span style="font-size:17pt;">발생함</span><span style="font-size:17pt;">(</span><span style="font-size:17pt;">조금</span><span style="font-size:17pt;"> </span><span style="font-size:17pt;">더</span><span style="font-size:17pt;"> </span><span style="font-size:17pt;">정확하게는</span><span style="font-size:17pt;">, </span><span style="font-size:17pt;">비율이</span><span style="font-size:17pt;"> 1</span><span style="font-size:17pt;">이</span><span style="font-size:17pt;"> </span><span style="font-size:17pt;">되는</span><span style="font-size:17pt;"> </span><span style="font-size:17pt;">사건이</span><span style="font-size:17pt;"> </span><span style="font-size:17pt;">발생할</span><span style="font-size:17pt;"> </span><span style="font-size:17pt;">확률이</span><span style="font-size:17pt;"> 1</span><span style="font-size:17pt;">이</span><span style="font-size:17pt;"> </span><span style="font-size:17pt;">됨</span><span style="font-size:17pt;">)</span><span style="font-size:17pt;">을</span><span style="font-size:17pt;"> </span><span style="font-size:17pt;">증명할</span><span style="font-size:17pt;"> </span><span style="font-size:17pt;">수</span><span style="font-size:17pt;"> </span><span style="font-size:17pt;">있습니다</span><span style="font-size:17pt;">.</span></p> <p style="margin:0px;font-size:17px;line-height:normal;color:#454545;"><span style="font-size:17pt;"></span><br></p> <ol start="2"><li style="margin:0px;font-size:17px;line-height:normal;color:#454545;"><span style="font-size:17pt;">A, B </span><span style="font-size:17pt;">두</span><span style="font-size:17pt;"> </span><span style="font-size:17pt;">사람이</span><span style="font-size:17pt;"> </span><span style="font-size:17pt;">동전을</span><span style="font-size:17pt;"> </span><span style="font-size:17pt;">던져서</span><span style="font-size:17pt;"> </span><span style="font-size:17pt;">내기를</span><span style="font-size:17pt;"> </span><span style="font-size:17pt;">합니다</span><span style="font-size:17pt;">. </span><span style="font-size:17pt;">앞면이</span><span style="font-size:17pt;"> </span><span style="font-size:17pt;">나오면</span><span style="font-size:17pt;"> B</span><span style="font-size:17pt;">가</span><span style="font-size:17pt;"> A</span><span style="font-size:17pt;">에게</span><span style="font-size:17pt;"> 100</span><span style="font-size:17pt;">원을</span><span style="font-size:17pt;"> </span><span style="font-size:17pt;">주고</span><span style="font-size:17pt;"> </span><span style="font-size:17pt;">뒷면이</span><span style="font-size:17pt;"> </span><span style="font-size:17pt;">나오면</span><span style="font-size:17pt;"> A</span><span style="font-size:17pt;">가</span><span style="font-size:17pt;"> B</span><span style="font-size:17pt;">에게</span><span style="font-size:17pt;"> 100</span><span style="font-size:17pt;">원을</span><span style="font-size:17pt;"> </span><span style="font-size:17pt;">줍니다</span><span style="font-size:17pt;">. </span><span style="font-size:17pt;">동전을</span><span style="font-size:17pt;"> </span><span style="font-size:17pt;">무한히</span><span style="font-size:17pt;"> </span><span style="font-size:17pt;">계속</span><span style="font-size:17pt;"> </span><span style="font-size:17pt;">던질</span><span style="font-size:17pt;"> </span><span style="font-size:17pt;">때</span><span style="font-size:17pt;"> </span><span style="font-size:17pt;">언젠가</span><span style="font-size:17pt;"> A</span><span style="font-size:17pt;">의</span><span style="font-size:17pt;"> </span><span style="font-size:17pt;">이익이</span><span style="font-size:17pt;"> 1</span><span style="font-size:17pt;">조원</span><span style="font-size:17pt;">(B</span><span style="font-size:17pt;">의</span><span style="font-size:17pt;"> </span><span style="font-size:17pt;">손실이</span><span style="font-size:17pt;"> 1</span><span style="font-size:17pt;">조원</span><span style="font-size:17pt;">)</span><span style="font-size:17pt;">이</span><span style="font-size:17pt;"> </span><span style="font-size:17pt;">되는</span><span style="font-size:17pt;"> </span><span style="font-size:17pt;">순간이</span><span style="font-size:17pt;"> </span><span style="font-size:17pt;">올</span><span style="font-size:17pt;"> </span><span style="font-size:17pt;">확률은</span><span style="font-size:17pt;">? </span><span style="font-size:17pt;">답</span><span style="font-size:17pt;">: 1</span></li></ol><p style="margin:0px;font-size:17px;line-height:normal;color:#454545;"><span style="font-size:17pt;"> A</span><span style="font-size:17pt;">가</span><span style="font-size:17pt;"> 1</span><span style="font-size:17pt;">조원을</span><span style="font-size:17pt;"> </span><span style="font-size:17pt;">벌</span><span style="font-size:17pt;"> </span><span style="font-size:17pt;">때까지</span><span style="font-size:17pt;"> </span><span style="font-size:17pt;">시행해야하는</span><span style="font-size:17pt;"> </span><span style="font-size:17pt;">경기수의</span><span style="font-size:17pt;"> </span><span style="font-size:17pt;">기대값은</span><span style="font-size:17pt;">? </span><span style="font-size:17pt;">답</span><span style="font-size:17pt;">:</span><span style="font-size:17pt;">무한대</span><span style="font-size:17pt;">(</span><span style="font-size:17pt;">언젠가는</span><span style="font-size:17pt;"> </span><span style="font-size:17pt;">그런</span><span style="font-size:17pt;"> </span><span style="font-size:17pt;">순간이</span><span style="font-size:17pt;"> </span><span style="font-size:17pt;">오지만</span><span style="font-size:17pt;"> </span><span style="font-size:17pt;">언제올지</span><span style="font-size:17pt;"> </span><span style="font-size:17pt;">모를</span><span style="font-size:17pt;"> </span><span style="font-size:17pt;">정도로</span><span style="font-size:17pt;"> </span><span style="font-size:17pt;">하염없이</span><span style="font-size:17pt;"> </span><span style="font-size:17pt;">기다려야합니다</span><span style="font-size:17pt;">.)</span></p> <p style="margin:0px;font-size:17px;line-height:normal;color:#454545;"><span style="font-size:17pt;">A </span><span style="font-size:17pt;">또는</span><span style="font-size:17pt;"> B</span><span style="font-size:17pt;">중에</span><span style="font-size:17pt;"> </span><span style="font-size:17pt;">먼저</span><span style="font-size:17pt;"> 1</span><span style="font-size:17pt;">조원을</span><span style="font-size:17pt;"> </span><span style="font-size:17pt;">버는</span><span style="font-size:17pt;"> </span><span style="font-size:17pt;">사람이</span><span style="font-size:17pt;"> </span><span style="font-size:17pt;">있으면</span><span style="font-size:17pt;"> </span><span style="font-size:17pt;">경기를</span><span style="font-size:17pt;"> </span><span style="font-size:17pt;">마치기로</span><span style="font-size:17pt;"> </span><span style="font-size:17pt;">했습니다</span><span style="font-size:17pt;">. </span><span style="font-size:17pt;">평균</span><span style="font-size:17pt;"> </span><span style="font-size:17pt;">경기횟수는</span><span style="font-size:17pt;">? </span><span style="font-size:17pt;">답</span><span style="font-size:17pt;">: 10^20</span><span style="font-size:17pt;">번</span><span style="font-size:17pt;"> </span></p> <p style="margin:0px;font-size:17px;line-height:normal;color:#454545;"><span style="font-size:17pt;">위</span><span style="font-size:17pt;"> </span><span style="font-size:17pt;">두</span><span style="font-size:17pt;"> </span><span style="font-size:17pt;">결과가</span><span style="font-size:17pt;"> </span><span style="font-size:17pt;">모순되어보이지만</span><span style="font-size:17pt;"> </span><span style="font-size:17pt;">신기하게</span><span style="font-size:17pt;"> </span><span style="font-size:17pt;">둘</span><span style="font-size:17pt;"> </span><span style="font-size:17pt;">다</span><span style="font-size:17pt;"> </span><span style="font-size:17pt;">사실입니다</span><span style="font-size:17pt;">. </span></p> <p style="margin:0px;font-size:17px;line-height:normal;color:#454545;"><span style="font-size:17pt;"></span><br></p> <p style="margin:0px;font-size:17px;line-height:normal;color:#454545;"><span style="font-size:17pt;">1</span><span style="font-size:17pt;">과</span><span style="font-size:17pt;"> </span><span style="font-size:17pt;">마찬가지로</span><span style="font-size:17pt;"> random walk</span><span style="font-size:17pt;">이론</span><span style="font-size:17pt;"> </span><span style="font-size:17pt;">또는</span><span style="font-size:17pt;"> </span><span style="font-size:17pt;">마팅게일</span><span style="font-size:17pt;"> </span><span style="font-size:17pt;">이론을</span><span style="font-size:17pt;"> </span><span style="font-size:17pt;">이용하면</span><span style="font-size:17pt;"> </span><span style="font-size:17pt;">증명할</span><span style="font-size:17pt;"> </span><span style="font-size:17pt;">수</span><span style="font-size:17pt;"> </span><span style="font-size:17pt;">있습니다</span><span style="font-size:17pt;">. </span></p> <p style="margin:0px;font-size:17px;line-height:normal;color:#454545;"><span style="font-size:17pt;"></span><br></p> <ol start="3"><li style="margin:0px;font-size:17px;line-height:normal;color:#454545;"><span style="font-size:17pt;">A, B </span><span style="font-size:17pt;">두</span><span style="font-size:17pt;"> </span><span style="font-size:17pt;">사람이</span><span style="font-size:17pt;"> </span><span style="font-size:17pt;">동전던지기</span><span style="font-size:17pt;"> </span><span style="font-size:17pt;">내기를</span><span style="font-size:17pt;"> </span><span style="font-size:17pt;">합니다</span><span style="font-size:17pt;">. </span><span style="font-size:17pt;">이번에는</span><span style="font-size:17pt;"> </span><span style="font-size:17pt;">승률만</span><span style="font-size:17pt;"> </span><span style="font-size:17pt;">기록합니다</span><span style="font-size:17pt;">. 99</span><span style="font-size:17pt;">번의</span><span style="font-size:17pt;"> </span><span style="font-size:17pt;">경기동안</span><span style="font-size:17pt;"> </span><span style="font-size:17pt;">어느</span><span style="font-size:17pt;"> </span><span style="font-size:17pt;">한</span><span style="font-size:17pt;"> </span><span style="font-size:17pt;">사람의</span><span style="font-size:17pt;"> </span><span style="font-size:17pt;">승률이</span><span style="font-size:17pt;"> </span><span style="font-size:17pt;">다른</span><span style="font-size:17pt;"> </span><span style="font-size:17pt;">사람의</span><span style="font-size:17pt;"> </span><span style="font-size:17pt;">승률보다</span><span style="font-size:17pt;"> </span><span style="font-size:17pt;">항상</span><span style="font-size:17pt;"> </span><span style="font-size:17pt;">크거나</span><span style="font-size:17pt;"> </span><span style="font-size:17pt;">같을</span><span style="font-size:17pt;"> </span><span style="font-size:17pt;">확률은</span><span style="font-size:17pt;">? </span><span style="font-size:17pt;">예를</span><span style="font-size:17pt;"> </span><span style="font-size:17pt;">들어</span><span style="font-size:17pt;"> 3</span><span style="font-size:17pt;">번의</span><span style="font-size:17pt;"> </span><span style="font-size:17pt;">경기를</span><span style="font-size:17pt;"> </span><span style="font-size:17pt;">해서</span><span style="font-size:17pt;"> </span><span style="font-size:17pt;">앞</span><span style="font-size:17pt;">,</span><span style="font-size:17pt;">앞</span><span style="font-size:17pt;">,</span><span style="font-size:17pt;">뒤가</span><span style="font-size:17pt;"> </span><span style="font-size:17pt;">나왔다면</span><span style="font-size:17pt;"> A</span><span style="font-size:17pt;">의</span><span style="font-size:17pt;"> </span><span style="font-size:17pt;">승률은</span><span style="font-size:17pt;"> 1,1,2/3 </span><span style="font-size:17pt;">이고</span><span style="font-size:17pt;"> B</span><span style="font-size:17pt;">의</span><span style="font-size:17pt;"> </span><span style="font-size:17pt;">승률은</span><span style="font-size:17pt;"> 0,0,1/3 </span><span style="font-size:17pt;">이런식으로</span><span style="font-size:17pt;"> </span><span style="font-size:17pt;">기록합니다</span><span style="font-size:17pt;"> </span><span style="font-size:17pt;">답</span><span style="font-size:17pt;">:</span><span style="font-size:17pt;">대략</span><span style="font-size:17pt;"> 16%</span></li></ol><p style="margin:0px;font-size:17px;line-height:normal;color:#454545;"><span style="font-size:17pt;">생각보다</span><span style="font-size:17pt;"> </span><span style="font-size:17pt;">큰</span><span style="font-size:17pt;"> </span><span style="font-size:17pt;">확률입니다</span><span style="font-size:17pt;">. 6</span><span style="font-size:17pt;">번</span><span style="font-size:17pt;"> </span><span style="font-size:17pt;">중에</span><span style="font-size:17pt;"> 1</span><span style="font-size:17pt;">번꼴로</span><span style="font-size:17pt;"> 99</span><span style="font-size:17pt;">번</span><span style="font-size:17pt;"> </span><span style="font-size:17pt;">연속해서</span><span style="font-size:17pt;"> </span><span style="font-size:17pt;">동전을</span><span style="font-size:17pt;"> </span><span style="font-size:17pt;">던지면</span><span style="font-size:17pt;"> </span><span style="font-size:17pt;">어느</span><span style="font-size:17pt;"> </span><span style="font-size:17pt;">한</span><span style="font-size:17pt;"> </span><span style="font-size:17pt;">사람의</span><span style="font-size:17pt;"> </span><span style="font-size:17pt;">승률이</span><span style="font-size:17pt;"> </span><span style="font-size:17pt;">항상</span><span style="font-size:17pt;"> </span><span style="font-size:17pt;">큽니다</span><span style="font-size:17pt;">. </span><span style="font-size:17pt;">직관적으로</span><span style="font-size:17pt;"> </span><span style="font-size:17pt;">생각하면</span><span style="font-size:17pt;"> </span><span style="font-size:17pt;">승률이</span><span style="font-size:17pt;"> </span><span style="font-size:17pt;">엎치락뒤치락</span><span style="font-size:17pt;"> </span><span style="font-size:17pt;">할</span><span style="font-size:17pt;"> </span><span style="font-size:17pt;">것</span><span style="font-size:17pt;"> </span><span style="font-size:17pt;">같지만</span><span style="font-size:17pt;"> </span><span style="font-size:17pt;">그럴</span><span style="font-size:17pt;"> </span><span style="font-size:17pt;">확률은</span><span style="font-size:17pt;"> </span><span style="font-size:17pt;">굉장히</span><span style="font-size:17pt;"> </span><span style="font-size:17pt;">낮습니다</span><span style="font-size:17pt;">. </span></p> <p style="margin:0px;font-size:17px;line-height:normal;color:#454545;"><span style="font-size:17pt;"></span><br></p> <ol start="4"><li style="margin:0px;font-size:17px;line-height:normal;color:#454545;"><span style="font-size:17pt;"></span><span style="font-size:17pt;">동전던지기는</span><span style="font-size:17pt;"> </span><span style="font-size:17pt;">아니지만</span><span style="font-size:17pt;"> 3</span><span style="font-size:17pt;">번</span><span style="font-size:17pt;"> </span><span style="font-size:17pt;">확률의</span><span style="font-size:17pt;"> </span><span style="font-size:17pt;">증명과</span><span style="font-size:17pt;"> </span><span style="font-size:17pt;">관련된</span><span style="font-size:17pt;"> </span><span style="font-size:17pt;">문제입니다</span><span style="font-size:17pt;">. Ballot theorem</span><span style="font-size:17pt;">이라고</span><span style="font-size:17pt;"> </span><span style="font-size:17pt;">굉장히</span><span style="font-size:17pt;"> </span><span style="font-size:17pt;">유명한</span><span style="font-size:17pt;"> </span><span style="font-size:17pt;">정리입니다</span><span style="font-size:17pt;">. 10000</span><span style="font-size:17pt;">명의</span><span style="font-size:17pt;"> </span><span style="font-size:17pt;">유권자가</span><span style="font-size:17pt;"> </span><span style="font-size:17pt;">후보</span><span style="font-size:17pt;"> A,B</span><span style="font-size:17pt;">에게</span><span style="font-size:17pt;"> </span><span style="font-size:17pt;">투표해서</span><span style="font-size:17pt;"> A</span><span style="font-size:17pt;">가</span><span style="font-size:17pt;"> 5500</span><span style="font-size:17pt;">표</span><span style="font-size:17pt;">, B</span><span style="font-size:17pt;">가</span><span style="font-size:17pt;"> 4500</span><span style="font-size:17pt;">표를</span><span style="font-size:17pt;"> </span><span style="font-size:17pt;">득표했다</span><span style="font-size:17pt;">. </span><span style="font-size:17pt;">개표과정에서</span><span style="font-size:17pt;"> A</span><span style="font-size:17pt;">가</span><span style="font-size:17pt;"> </span><span style="font-size:17pt;">첫개표에서</span><span style="font-size:17pt;"> 10000</span><span style="font-size:17pt;">번째</span><span style="font-size:17pt;"> </span><span style="font-size:17pt;">표를</span><span style="font-size:17pt;"> </span><span style="font-size:17pt;">개표할</span><span style="font-size:17pt;"> </span><span style="font-size:17pt;">때까지</span><span style="font-size:17pt;"> </span><span style="font-size:17pt;">항상</span><span style="font-size:17pt;"> </span><span style="font-size:17pt;">선두를</span><span style="font-size:17pt;"> </span><span style="font-size:17pt;">유지할</span><span style="font-size:17pt;"> </span><span style="font-size:17pt;">확률은</span><span style="font-size:17pt;">? </span><span style="font-size:17pt;">답</span><span style="font-size:17pt;"> :(<a>5500-4500</a>)/10000=1/10</span></li></ol><p style="margin:0px;font-size:17px;line-height:normal;color:#454545;"><span style="font-size:17pt;">마찬가지로</span><span style="font-size:17pt;"> </span><span style="font-size:17pt;">생각보다</span><span style="font-size:17pt;"> </span><span style="font-size:17pt;">큰</span><span style="font-size:17pt;"> </span><span style="font-size:17pt;">확률입니다</span><span style="font-size:17pt;">. </span></p> <p style="margin:0px;font-size:17px;line-height:normal;color:#454545;"><span style="font-size:17pt;"></span><br></p> <p style="margin:0px;font-size:17px;line-height:normal;color:#454545;"><span style="font-size:17pt;">Feller, An introduction to probability theory and its application vol1 chapter3</span><span style="font-size:17pt;">를</span><span style="font-size:17pt;"> </span><span style="font-size:17pt;">참고하시면</span><span style="font-size:17pt;"> </span><span style="font-size:17pt;">필요한</span><span style="font-size:17pt;"> </span><span style="font-size:17pt;">증명을</span><span style="font-size:17pt;"> </span><span style="font-size:17pt;">찾을</span><span style="font-size:17pt;"> </span><span style="font-size:17pt;">수</span><span style="font-size:17pt;"> </span><span style="font-size:17pt;">있습니다</span><span style="font-size:17pt;">. 위 문제들에서 동전은 완벽하게 공평한 동전입니다. 앞/뒤 확률이 1/2이 아니면 성립하지 않습니다. </span></p> <div><span style="font-size:17pt;"><br></span></div>