Simple apex Utility to calculate Standard Deviation

StandardDeviationComputation

public with sharing class StandardDeviationComputation {
    public static decimal getStandardDeviation(Integer precision){
        AggregateResult[] groupedResults = [SELECT COUNT(Id),SUM(DistanceSquare__c) FROM Survey__c  GROUP BY Standard_Deviation__c ];
        decimal sumOfDistanceSquare = (decimal)groupedResults[0].get('expr1');
        integer count = (integer)groupedResults[0].get('expr0');
        if(count > 0){
            return system.Math.sqrt(sumOfDistanceSquare/count).setScale(precision);//Scale is kept at 3 currently
        }else{
            return 0;
        }
    }
}