For any 3 given numbers, which of the following is always equivalent to adding the 3 numbers together and then dividing the sum by 3 ？（）
Ⅰ. Ordering the 3 numbers numerically, from highest to lowest, and then selecting the middle number.
Ⅱ. Dividing each of the numbers by 3 and then adding the results together.
Ⅲ. Multiplying each number by 6, adding the resulting products together, and then dividing the sum by 9.
A. Ⅰ only
B. Ⅱ only
C. Ⅰ and Ⅱ only
D. Ⅱ and Ⅲ only
E. None of the above
参考答案：B
解析：
Choose any three numbers and test them on statements Ⅰ, Ⅱ, and Ⅲ. You will quickly find that Ⅰ and Ⅲ are not always true. Ⅱ is always true, because mathematically it and the process in the question are doing the same thing--summing the numbers and dividing by 3.