An old co-worker uses this as his interview question and I'm curious about how you might solve it.

"Given an array of integers, find the mean and the frequency"

The mean is very simple, but the frequency part is where different methodologies can come in.  Feel free to show and explain your process.  There is no right or wrong way, it's just a test of your intelligence/creativity.  

//TODO: Find the frequency

int[] intArray

int meanDivisor = intArray.Count();
int meanToBeDivided = 0;

foreach(int number in intArray)
    meanToBeDivided += number;

var mean = meanToBeDivided / meanDivisor;