C :

#include<stdio.h>
#define M 40
#define N 11
int Mean(int answer[],int n);
int Median(int answer[],int n);
int Mode(int answer[],int n);
void DataSort(int a[],int n);
int main()
{
	int i,feedback[M];
	for(i=0;i<M;i++)
	{
		scanf("%d",&feedback[i]);
	}
	printf("%d\n",Mean(feedback,M));
	printf("%d\n",Median(feedback,M));
	printf("%d\n",Mode(feedback,M));
	return 0;
}
int Mean(int answer[],int n)
{
	int i,sum=0;
	for(i=0;i<n;i++)
	{
		sum+=answer[i];
	}
	return n>0?sum/n:-1;
}
int Median(int answer[],int n)
{
	DataSort(answer,n);
	if(n%2==0)
	    return (answer[n/2]+answer[n/2-1])/2;
	else
	    return answer[n/2];
} 
int Mode(int answer[],int n)
{
	int i,grade,max=0,modeValue=0,count[N]={0};
	for(i=0;i<n;i++)
	{
		count[answer[i]]++;
	}
	for(grade=1;grade<=N-1;grade++)
	{
		if(count[grade]>max)
	    {
	    	max=count[grade];
	    	modeValue=grade;
	    }
	}
	return modeValue;
}
void DataSort(int a[],int n)
{
	int i,j,k,temp;
	for(i=0;i<n-1;i++)
	{
		k=i;
		for(j=i+1;j<n;j++)
		{
			if(a[j]>a[k]) k=j;
		}
		if(k!=i)
		{
			temp=a[k];
			a[k]=a[i];
			a[i]=temp;
		}
	}
}