How can I find the average in the ARRAYS?

I have already wrote the main funstion but I cannot figure out what to put in the other function to find the average of the three arrays?#include <iostream>

#include <iomanip>

using namespace std;

double avg1( double [], int);

double avg2( double [], int);

double avg3( double [], int);

double computeAverage(int [], double []);

int main()

{

double x[] = { 11.11, 66.66, 88.88, 33.33, 55.55 };

double y[] = { 9, 6, 5, 8, 3, 4, 7, 4, 6, 3, 8, 5, 7, 2 };

double z[] = { 123, 400, 765, 102, 345, 678, 234, 789 };

cout << fixed << setprecision(2);

double avg1 = computeAverage (x, sizeof (x) / sizeof (x[0]) );

double avg2 = computeAverage (y, sizeof (x) / sizeof (x[0]));

cout << "Average of numbers in array x = " << avg1 << '\n';

cout << "Average of numbers in array y = " << avg2 << '\n';

cout << "Average of numbers in array z = "

<< ComputeAverage (z, sizeof (z) / sizeof (z[0])) << '\n';

return 0;

}

double computeAverage ()

{

}

Any help would be appreciated.

Thanks,

Nate2430