IR 24A 解题捷径没看懂 求助！

april427

IR 24A 问题：For the 22 earthquakes, the arithmetic mean of the depths is greater than the median of the depths？

分别求出arithmetic mean 和median 然后比大小就OK.  求arithmetic mean的常规方法即22个数字之和除以22，但由于数字较大，算起来麻烦。
答案解释中给出了shortcut，但我没理解，高亮部分什么意思？求教大家~~

答案的方法为：The arithmetic mean of the depths is 1/22 times the sum of all 22 depths; therefore, it must be greater than1/22 times the greatest depth listed. But this last value- that is 1/22 (641)km is already greater than the median depth, so the arithmetic mean must be greater than the median of the depths.

april427

顶下 请大家帮忙看下~