Computed variance is slightly off

[write.me]

This code calculated the variance to be 9.75. It really is 9.3, what am I doing wrong?

 static double computeVariance(ref double Variance, params int[] intValues)
        {

           int sum = 0;
            for (int n = 0; n < intValues.Length; n++)
            {
                sum += intValues[n];
            }
            double avg = sum / intValues.Length;
            double varSum = 0;
            for (int v = 0; v < intValues.Length; v++)
                {
                    double diff = ((double)intValues[v] - avg);
                    varSum += (diff * diff);
                }
                Variance = varSum / (intValues.Length - 1);
                return Variance;

        }
        static void Main(string[] args)
        {
            double myInts = 0;
            double Variance = computeVariance(ref myInts, 1, 5, 2, 7, 8);
           Console.WriteLine("The variance is " + Variance);



            Console.ReadKey();

[tinstaafl]

Try this:

 static double computeVariance(ref double Variance, params int[] intValues)
{
    int sum = 0;
    for (int n = 0; n < intValues.Length; n++)
    {
        sum += intValues[n];
    }
    double avg = (double)(sum) / (double)(intValues.Length);
    double varSum = 0;
    for (int v = 0; v < intValues.Length; v++)
    {
        double diff = ((double)intValues[v] - avg);
        varSum += (diff * diff);
    }
    Variance = varSum / (double)(intValues.Length - 1);
    return Variance;
}           

BTW I think you posted this in the wrong section, it should be in C#