mean function

例句：

1. 1. The meaning of life is to find happiness in all things.
   生活的意义在于一切事物中寻找幸福。
2. 2. The function of the brain is to process information.
   大脑的功能是处理信息。
3. 3. The mean value of a set of numbers is the average of those numbers.
   一组数字的平均值是这些数字的平均数。