Say I have a set of data that is the price of a home.

100,000
125,000
92,000
175,000
135,000
10,000
500,000

Well, I know that the 10,000 fiqure is really just for a lot. So when figuring trends, I need to throw it out. I also know that the 500,000 fiqure is also way off, so it too needs to be thrown out.

If each of these numbers were in a field in a dbf(one per record) How could I programmatically throw out numbers that were way off? I have tried diffrent forms of average and standard deviation, but nothing seems quite right. I need some high school algebra or statistics lessons I think.