probably something simple I'm overlooking

I can't seem to figure out what I am doing wrong with passing the parameters between functions. I know that the calculations are correct (they are simple) and in the getTestScores function I went ahead and tested the calculations to make sure. It seems like the values for test1, 2 and 3 aren't being stored in memory as whatever I input gives a value of 0. getTestScores and displayAverage both need to be void functions and that's what I'm struggling with I think.

-------------------------Here's the code-------------------------

Code:

`#include <iostream>`

#include <iomanip>

using std::cout;

using std::cin;

using std::endl;

using std::fixed;

using std::setprecision;

//function prototypes

void getTestScores (double, double, double);

double calcAverage (double, double, double, double);

void displayAverage (double); //void function, no return value to main.

int main()

{

//declare variables & initialize

double average = 0.0;

double test1 = 0.0;

double test2 = 0.0;

double test3 = 0.0;

//call function to get test scores

getTestScores (test1, test2, test3);

//call function to calculate average

calcAverage (average, test1, test2, test3);

//call function to display average

displayAverage (average);

system ("pause");

return 0;

} //End of the main function

//*************************Function Definitions**********************

//Get Test Scores function

void getTestScores (double test1, double test2, double test3)

{

cout << "Enter the first test score: ";

cin >> test1;

cout << "Enter the second test score: ";

cin >> test2;

cout << "Enter the third test score: ";

cin >> test3;

} //end of getTestScores function

//Calculate Average function (return average value)

double calcAverage (double average, double test1, double test2, double test3)

{

average = (test1 + test2 + test3) / 3;

return average;

} //end of calcAverage function

//Display Average function (double)

void displayAverage (double average)

{

cout << "The average of the three scores you entered is: " << average << endl;

} //end of displayAverage function

Any help would be greatly appreciated by this noob!