for n=3,15,50,85, and 97, the nth percentile in height for a given age is the unique height among boys of that age that is greater than or equal to n percent, and less than or equal to (100-n) percent, of heights of boys of that age. 它使得至少有p%的数据项小于或等于这个值,且至少有(100-p)%的数据项大于或等于这个值。 n表示身高百分比(占所有同龄人的百分比),