How about this
A B
1 10 10
2 100 5
3 59 7.277777778

Formula in B3 will be =PERCENTILE(B1:B2,1-(A3-A1)/(A2-A1))
i tried 10 abd 100 in A3 and it does give the correct answer.

"dgold82" wrote:

I am looking for a business formula: Basically, I am trying to figure out the
best bulk discount per unit as possible to maximize profit.

For example: 10 units would sell for $10 dollars each. 100 units would sell
for $5 dollars each.

If I left a cell blank for units and put it 59 I want excel to calculate
what the cost would be based on the above range ($10 - $5) on a sliding scale
for discount. This might be simple but I am having a hard time wrapping my
brain around the formula.

Thank!.