# Field Manual for Hackers

## java array | Find the statement deviation of given N numbers.

1. import java.util.Scanner;
import java.lang.Math;
class Test1{
public static void main(String a[]){
int ar[]=new int[100];
int i,number;
double sum=0,mean,sd,difference=0;
System.out.print("Enter the number of elements: ");
Scanner o=new Scanner(System.in);
number=o.nextInt();
System.out.println("Now enter the values of array: ");
for(i=0;i<number;i++){
ar[i]=o.nextInt();
sum+=ar[i];
}
mean=sum/number;
for(i=0;i<number;i++){
difference+=(mean-ar[i])*(mean-ar[i]);
}
sd=difference/number;
double result=Math.sqrt(sd);
System.out.print("The standard deviation is: "+result);

}
}

OUTPUT
Enter the number of elements: 5
Now enter the values of array:
12 54 61 34 12
The standard deviation is: 20.470466531078376

2. import java.util.Scanner;
class StandardDev
{
public static void main(String args[])
{int sum=0;double Total=0,Average,New,NewTotal=0;
Scanner scan=new Scanner(System.in);
System.out.println("How many number you want to add");
int n=scan.nextInt();
int ar[]=new int[n];
System.out.println("Enter Numbers");
for (int i=0;i<n;i++)
{
ar[i]=scan.nextInt();
sum+=ar[i];
}
Average=sum/n;
for (int i=0;i<n;i++)
{
New=ar[i]-Average;
NewTotal+=(New*New);
}
NewTotal=NewTotal/n;
Total=Math.sqrt(NewTotal);
}
}

3. import java.util.Scanner;
class standarddeviation
{
public static void main(String args[])
{
Scanner scan=new Scanner(System.in);
System.out.println("How many number you want to add");
int n=scan.nextInt();
double ar[]=new double[n];
double sum = 0;
double mean =0;
double difference =0;
double mean2 = 0;
double sd; //standard deviation
System.out.println("Enter elements in array");
for (int i=0;i<n;i++)
{
ar[i]=scan.nextDouble();
sum += ar[i];
}
mean = sum/n;
for (int i=0;i<n;i++)
{
difference +=(ar[i]-mean) * (ar[i]-mean);
}
mean2 = difference/n;
sd = Math.sqrt(mean2);
System.out.println("the standard deviation of the numbers is :" +sd);
}
}

OUTPUT:
How many number you want to add
9
Enter elements in array
4 9 11 12 17 5 8 12 14
the standard deviation of the numbers is :3.9377878103709665

4. This comment has been removed by the author.

5. imnport java.util.Scanner;
class A
{
public static void main(String args[])
{
Scanner obj=new Scanner(System.in);
int n,i,val=0,goat,rate,avg=0;
System.out.println("Enter the value of n");
n=obj.nextInt();
int arr[]=new int[n];
System.out.println("Enter the array");
for(i=0;i<n;i++)
{
arr[i]=obj.nextInt();
sum+=arr[i];
}
System.out.println("The sum is"+sum);
avg=sum/n;
System.out.println("The average is="+avg);
for(i=0;i<n;i++)
{
goat=arr[i]-avg;
val=val+(goat*goat);
}
val=val/n;
rate=math.sqrt(val);
System.out.println("The standard deviation is="+rate);
}
}

6. import java.util.Scanner;
import java.lang.Math;
class Standard
{
public static void main(String Args[])
{
System.out.println("How many numbers you want to enter?");
Scanner sc=new Scanner(System.in);
int n=sc.nextInt();
int Ar[]=new int[n];
int sum=0,i,difference=0;
double total,result;
float avg;
System.out.println("enter the values");
for(i=0;i<n;i++)
{
Ar[i]=sc.nextInt();
}
for(i=0;i<n;i++)
{
sum+=Ar[i];
}
avg=sum/n;
for(i=0;i<n;i++)
{
difference+=((Ar[i]-avg)*(Ar[i]-avg));
}
total=difference/n;
result=Math.sqrt(total);
System.out.println("standard deviation is "+result);
}}

7. import java.util.Scanner;
class Standard{
public static void main(String arr[]){
Scanner obj=new Scanner(System.in);
int n,i,sum=0;
double mean,variance=0,std;
System.out.println("enter the value of n");
n=obj.nextInt();
int ar[]=new int[n];
System.out.println("enter the value of elements of aray");
for(i=0;i<n;i++)
ar[i]=obj.nextInt();
for(i=0;i<n;i++){
sum=sum+ar[i];}
mean=sum/n;
for(i=0;i<n;i++)
variance=(Math.pow((ar[i]-mean),2))/n;
std=Math.sqrt(variance);
System.out.println("the standard deviation is "+std);
}

}

8. import java.util.Scanner;
class Sd{
public static void main(String args[]){
int size=0,i=0,n,subtract=0,square,mean=0,sum=0;
double divide=0,sum1=0,squareroot=0;
Scanner scan=new Scanner(System.in);
System.out.println("enter the size of array");
size=scan.nextInt();
int ar[]=new int[size];
for(i=0;i<size;i++)
{
System.out.println("enter the value"+(i+1));
ar[i]=scan.nextInt();
sum=sum+ar[i];
}
{
mean=sum/size;
System.out.println("mean is:"+mean);
}

for(i=0;i<size;i++)
{
subtract=(ar[i]-mean);
square=(int) Math.pow(subtract,2);
sum1=sum1+square;
divide=sum1/size;
squareroot= Math.sqrt(divide);
}
System.out.printf("\n value"+squareroot);
}
}