The answer for the above question as i did is as follows

import java.util.*;

class ClassStatistics

{

public static void main(String args[])

{

float marks[]=new float[20];

int i,ctr=0,ctr1=0,ctr2=0,ctr3=0,passed=0;

float highest=0, lowest;

Scanner input=new Scanner(System.in);

for(i=0;i<20;i++)

{


System.out.println("Enter the marks of student");

System.out.println("Enter a mark greater than 100 to view results");

marks[i]=input.nextFloat();


if(marks[i]>=0&&marks[i]<=29)

ctr++;

else if(marks[i]>=30&&marks[i]<=39)

ctr1++;

else if(marks[i]>=40&&marks[i]<=69)

ctr2++;

else if(marks[i]>=70&&marks[i]<=100)

ctr3++;

if(marks[i]>100)

break;

if(marks[i]>=50)

passed++;

if(marks[i]>=highest)

highest=marks[i];

}

System.out.print("0-29 ");

while(ctr!=0)

{

System.out.print("*");

ctr--;

}

System.out.println("");

System.out.print("30-39 ");

while(ctr1!=0)

{

System.out.print("*");

ctr1--;

}

System.out.print("");

System.out.print("40-69 ");

while(ctr2!=0)

{

System.out.print("*");

ctr2--;

}

System.out.print("");

System.out.print("70-100 ");

while(ctr3!=0)

{

System.out.print("*");

ctr3--;

}

int j=0;

lowest=marks[j];

j++;

while(j<20)

{

if(marks[j]<=lowest)

lowest=marks[j];

j++;

}


System.out.println("Number of students passing "+passed);

System.out.println("Highest mark "+highest);

System.out.println("Lowest mark "+lowest);


}

}