數字陣列1：
Array ( [0] => 2 [1] => 8 [2] => 7 [3] => 6 [4] => 5 [5] => 6 [6] => 4 )
數字陣列2：
Array ( [0] => 9 [1] => 2 [2] => 8 [3] => 7 [4] => 6 [5] => 5 [6] => 6 [7] => 4 )
my_mean_1=5.4285714285714
my_mean_2=5.875