數學統計學問題！！

1) x-8,x-2,x+3及x+7的平均數 就係 (x-8+x-2+x+3+x+7)/4 = x

第一个數 偏差 = | (x- 8 ) -x | = 8 , 如此類推 ...

so 平均偏差 = (8 + 2 + 3 + 7 ) /4 = 5

2) Let x be the first number,

then the probability second number not equal to x = 5/6

let y be the second number,

then the probability third number not equal to x and y = 4/6

so the probability of 3 different numbers = (5/6) * (4/6) = 20/36 = 5/9