Your son has secured the fourth rank in the class. There are twenty students in the class. Hence 15 students are below him or 80% of students are below him. Now, your son is said to at the "80th percentile".Percentile: The value below which a percentage of data falls.Formula:Percentile = (Number of values below "x"/total number of values)*100In our case =(16/20)*100 =80 Suppose, your son has scored...