Average function?

The Mighty Dubs

Hi
I m currently creating an ASP page which Im using VB Script with. I need to come up with a way to calculate an average of an ever changing amount of fields. The total sum is made up of a max of 3 different figures depending on the item you choose.
e.g. item1 is made up of a unitcost, printcost and freightcharge. Each cost is margined. so to say for arguements sake each cost had a % margin of 20%, then you would add 20+20+20 & divide by 3.
Now Item2 might only have unitcost and freight charge, so Id be adding up only 2 margins and dividing by 2. and so on...

Is there a way I can determine the amount of fields and average the margins depending on the amount of fields in the equation

Any ideas

pH

Just count the number of items and divide at the end:

total = 0
count = 0;
avg = 0;
for each item {
 total = total + margin
 count++
}
if (count > 0) {
 avg = total / count
}

However, adding the margin percentages together and dividing at the end will not give you a meaningful figure - average or otherwise. To calculate an average margin you need to add the actual amounts (in cents) together and divide by the total amount. Adding percentages together will give a meaningless result.