First u have to enter ten student mark.this will calculate lowest mark, highest mark, mean mark::

#include<conio.h>

#include<stdio.h>

void main()

{clrscr();

int a[10],i,n,m;

float b;

printf("enter the numbers of 10 students");

n=1;

for(i=0;i<=9;i++)

{printf("\n %d.",n);

scanf("%d",&a[i]);

n++;}

n=1;

for(i=0;i<=9;i++)

{printf("\n %d.",n);

printf("%d",a[i]);

n++;}

printf("\n \n calculation of highest marks");

m=a[0];

for(i=0;i<=9;i++)

{if(m<a[i])

m=a[i];}

printf("\n %d",m);

printf("\n \n calculation for lowest marks");

m=a[0];

for(i=0;i<=10;i++)

{if(m>a[i])

m=a[i];}

printf("\n %d",m);

printf("\n \n calculation of mean of the marks");

m=0;

for(i=0;i<=9;i++)

{m=m+a[i];}

b=m/10;

printf("\n %f",b);

getch();}