weiye有些地方寫錯了，\( x-y=-1 \)，\( x-y=1 \)，\( (n-2)^3 \)等
我將立體圖做成動畫，能看出為什麼重新組合後會是個立方體
附上中英文題目，讓更多網友也能搜尋到這篇
從區間[0,n]中隨意取出三個實數x, y及z, 其中n為某正整數。若x, y, z中沒有兩數之差的絕對值小於1的機率大於\( \displaystyle \frac{1}{2} \)，則n的最小值為何？
(A)7 (B)8 (C)9 (D)10 (E)11
Real numbers x,y, and z are chosen independently and at random from the interval [0,n] for some positive integer n. The probability that no two of x,y and z are within 1 unit of each other is greater than \( \displaystyle \frac{1}{2} \). What is the smallest possible value of n?
(A)7 (B)8 (C)9 (D)10 (E)11
Art of Problem Solving: 2012 AMC 10 A #25
http://www.youtube.com/watch?v=HOtyh9qycrI
