A consideration about picking up the `best' values from N times experiences. Mathematically, the author considered "how the maximum value of N values that are distributed normally distributes?". The median values are 0.998, 1.498, 1.998 for N=4,10,30, respectively.
This proposition would be useful because everybody quite often is in need of choosing something best from multiple candidates in their daily or social life. The figures shown above are easy to remember so you can utilize them with ease.