Char Function, number to letter grades - function

Question

I am relatively new to c++ programming and I am struggling with my code. The objective of this code is to take scores input by the user and calculate the mean, the standard deviation and converting it to a letter grade using the calculations under char gradeFunction. When i try to debug this program using visual studios 2013, i am having a couple problems with the the gradefunction. Again i am new to programming so troubleshooting errors is very hard for me and I would appreciate any help or advice! The program looks like this so far.
#include <iostream>
#include <iomanip>
#include <cmath>
#include <string.h>
#include <string>
using namespace std;
void printArray(int Array[], int count);
double average(double scoreTotal, int count);
double stddev(int Array[], int count, double mean);
char gradeFunction(int scores, double stddev, double mean);
int main()
{
int scores[8];
int count;
double scoreTotal = 0;
int standarddev[8];
double mean;
cout << "Enter scores seperated by blanks:" " ";
for (count = 0; count <= 7; count++)
{
cin >> scores[count];
scoreTotal += scores[count];
mean = scoreTotal / 8;
}
cout << endl;
cout << "Grade Scores by Student" << endl;
cout << "Score" "\t" "Grade" << endl;
cout << "----------------------------------" << endl;
printArray(scores, 8);
cout << gradeFunction(scores, stddev, mean);
cout << endl;
cout << "The mean is" " "<< fixed << setprecision(1) << average(scoreTotal, count) << endl;
cout << "The standard deviation is" " " << stddev(scores, count, mean) << endl;
cout << endl;
system("pause");
return 0;
}
void printArray(int Array[], int count)
{
for (int x = 0; x < count; x++)
{
cout << fixed << setprecision(1) << Array[x] << endl;
}
}
char gradeFunction(int scores, double stddev, double mean)
{
char F, D, C, B, A;
if (scores <= (mean - (1.5 * stddev)))
return 'F';
else if (scores <= (mean - (.5 * stddev)))
return 'D';
else if (scores <= (mean + (.5 * stddev)))
return 'C';
else if (scores <= (mean + (1.5 * stddev)))
return 'B';
else return 'A';
}
double average(double scoreTotal, int count)
{
return scoreTotal / count;
}
double stddev(int Array[], int count , double mean)
{
double stddev;
double sum2 = 0;
for (int i = 0; i < count; i++)
{
sum2 += pow((Array[i] - mean), 2);
}
stddev = sqrt(sum2 / (count - 1));
return stddev;
}
The error messages this leaves me with are...
3 IntelliSense: argument of type "double (*)(int *Array, int count, double mean)" is incompatible with parameter of type "double"
Error 1 error C2664: 'char gradeFunction(int [],double,double)' : cannot convert argument 2 from 'double (__cdecl *)(int [],int,double)' to 'double'