Assignment Questions:

4. Calculate each student letter grade using a function, save the letter grade to another array defined in main function.
5. Return the count of the grades for each letter grade (A, B, C,D, F) using a function
6. Perform a selection sort on the number grade array into descending order and output them again using functions.


I need some help on the last 3 questions of my assignment and I cannot figure out how to do it. Here's my code so far. I just don't know how to save them in an array etc. Other than that the program ran fine before I started adding the last few steps

Code:
#include <iostream>
#include <cmath>
#include <string>
#include <math.h>

using namespace std;
//Global Function
void averageMaxCalc(int scoreInput[5], int sumZ, double& sAverage, double& sAverageF);
void studentScoreCalc(int scoreInput[5], int sum);//Function studentScore()
void deviation(int scoreInput[5], int sum);
int letterGradesA(int scoreInput[5], char letterDefined);

//|=======================|
//|======== Main =========|
//|=======================|
int main (char LetterDefined)
{
	cout << "Welcome to the student score calculator program.\n\n";
	//Variables
	int scoreInput[5], sum = 0, sumZ = 0;
	double sAverage, sAverageF;

	//Defined
	char letterDefined;
	char letterGrades[6];
	for (int m = 0; m < 6; ++m) 
	{
		letterDefined = letterGrades[m];
	}


	//Functions Within Main()
	studentScoreCalc(scoreInput, sum);//Function StudentScore()
	averageMaxCalc(scoreInput, sumZ, sAverage, sAverageF);//Function averageMaxCalc()
	deviation(scoreInput, sum);//Function deviation()
	//letterGradesA() returned
	letterGradesA(scoreInput, letterDefined);

	system("pause");
	return 0;

}
//|=====================================|
//|=== 1. Student Input and Max/Less ===|
//|=====================================|
void studentScoreCalc(int scoreInput[5], int sum)
{
	//Declearing Variables
	sum = 0;

	cout << "Please Enter Student Scores below: \n";//Outputs to Console
	//Sum is set to 0

	//Looping countScore and i 15x
	for (int i = 0; i <5; i++)
	{
		cin >> scoreInput[i];//Creates User Input
		
	}
}

//|=================================|
//|=== 2. Funtion averageMaxCalc ===|
//|=================================|
void averageMaxCalc(int scoreInput[5], int sumZ, double& sAverage, double& sAverageF)
{
	sumZ = 0;//Set sumZ to 0;

	//Gets Sum Of All Numbers
	sumZ = scoreInput[0]+scoreInput[1]+scoreInput[2]+scoreInput[3]+scoreInput[4];
	//Finds The Average
		sAverage = sumZ / 5;//Finds Average
		sAverageF = (sumZ%5)*2;//Finds Decimal
		cout << "The Sum Of All Scores Is: " <<sumZ << "\n"
			 << "The Average Is: " << sAverage << "." << sAverageF << endl; 
}
//|===================================|
//|=== 3. Calculation of Deviation ===|
//|===================================|
	void deviation(int scoreInput[5], int sum)
	{
		double eX2Input;
		double eXInput;
		double variance;
		double sDeviation;

		//Gets EX^2
		eX2Input = pow(scoreInput[0], 2) + pow(scoreInput[1], 2) + pow(scoreInput[2], 2) + pow(scoreInput[3], 2) + pow(scoreInput[4],2);
		eXInput = scoreInput[0] + scoreInput[1] + scoreInput[2] + scoreInput[3] + scoreInput[4];
		variance = (5*(eX2Input)-(eXInput))/(5 * (5-1));//Calculates Variance
		sDeviation = sqrt(variance);//Calculates Standard Deviation
		//Testing output
		cout << "The Standard Deviation is: " << sDeviation << endl;
	}
//|===============================================|
//|======= 4. Grades Converted To Letters ========|
//|===============================================|
int letterGradesA(int scoreInput[5], char letterDefined)
{

	if(scoreInput[0] <= 100)
		scoreInput[0] = 'A';
	else if(scoreInput[0] < 90)
		scoreInput[0] = 'B';
	else if(scoreInput[0] < 80)
		scoreInput[0] = 'C';
	else if(scoreInput[0] < 70)
		scoreInput[0] = 'D';
	else if(scoreInput[0] < 60)
		scoreInput[0] = 'F';

	if(scoreInput[1] <= 100)
		scoreInput[1] = 'A';
	else if(scoreInput[1] < 90)
		scoreInput[1] = 'B';
	else if(scoreInput[1] < 80)
		scoreInput[1] = 'C';
	else if(scoreInput[1] < 70)
		scoreInput[1] = 'D';
	else if(scoreInput[1] < 60)
		scoreInput[1] = 'F';

	if(scoreInput[2] <= 100)
		scoreInput[2] = 'A';
	else if(scoreInput[2] < 90)
		scoreInput[2] = 'B';
	else if(scoreInput[2] < 80)
		scoreInput[2] = 'C';
	else if(scoreInput[2] < 70)
		scoreInput[2] = 'D';
	else if(scoreInput[2] < 60)
		scoreInput[2] = 'F';

	if(scoreInput[3] <= 100)
		scoreInput[3] = 'A';
	else if(scoreInput[2] < 90)
		scoreInput[3] = 'B';
	else if(scoreInput[2] < 80)
		scoreInput[3] = 'C';
	else if(scoreInput[2] < 70)
		scoreInput[3] = 'D';
	else if(scoreInput[2] < 60)
		scoreInput[3] = 'F';

	if(scoreInput[4] <= 100)
		scoreInput[4] = 'A';
	else if(scoreInput[2] < 90)
		scoreInput[4] = 'B';
	else if(scoreInput[2] < 80)
		scoreInput[4] = 'C';
	else if(scoreInput[2] < 70)
		scoreInput[4] = 'D';
	else if(scoreInput[2] < 60)
		scoreInput[4] = 'F';

	char letterGrade[][6] = {'A', 'B', 'C', 'D', 'F'};

	return letterGradesA(scoreInput, letterDefined);

}