Question

**** Using java

write a program that finds the standard deviation of a set of numbers. it also has to prompt the user to enter a set of numbers.

Answer 1

import java.util.Scanner;

public class StandardDeviation {
    private static double mean(double arr[]){
        int n = arr.length;
        double sum = 0;
        for(int i = 0;i<n;i++){
            sum += arr[i];
        }
        return sum / n;
    }

    private static double standardDeviation(double arr[]){
        int n = arr.length;
        double res = 0;
        double m = mean(arr);
        for(int i = 0;i<n;i++){
            res += Math.pow(arr[i]-m,2);
        }
        return (float) Math.sqrt(res/ (n-1));
    }

    public static void main(String args[]){
        int n;
        Scanner scanner = new Scanner(System.in);
        System.out.print("How many input numbers: ");
        n = scanner.nextInt();

        double arr[] =  new double[n];
        System.out.print("Enter "+ n +" numbers: ");
        for(int i = 0;i<n;i++){
            arr[i] = scanner.nextDouble();
        }

        System.out.println("Standard deviation: "+ standardDeviation(arr));
    }
}

Output:

How many input numbers: 4 Enter 4 numbers: 34 56 7890 Standard deviation: 24.731895446777344