Heres is the basic logic required, if I am understanding your question right...

//declare an array of type float
float[] maxValues;
float average, sum;

//in the setup assign a values variables
maxValues = new float[numberOfValues];
average = 0;
sum = 0;

//in the loop assign a value to each index in the "maxValues" array

for(int i = 0; i < maxValues.length) {
 maxValues[i] = maxValue;
}

//to calculate the average sum all the values inside the maxValues array

for(int i = 0; i < maxValues.length) {
 sum += maxValues[i];
}

average = sum/maxValues.length

still the same logic applies. you would store each max value in the "maxValue" array once the max has been calculated.