OJ Board

i think it's very easy,but...
this is my code,can anybody tell me why?

#include<stdio.h>
int main()
{
int sum=0;
int a[100];
int i,j,k,c;
scanf("%d",&i);
for(k=0;k<i;k++)
{
scanf("%d",&j);
for(k=0;k<j;k++)
{
scanf("%d",&a[k]);
sum+=a[k];
}
c=0;
for(k=0;k<j;k++)
{
if(a[k]>float(sum/j ...