average is about 100, although iq tests aren't very accurate. Ive done loads of them and scored between 130 and 160. My average is 148 but i think they just prove that you are good or bad at doing IQ tests.
As avaiator said, they can vary greatly as I have had very different results on different tests. I think a proper mensa test would be the most accurate.
I agree with the other posts, psychometric testing only really tests how good you are at the tests. If you keep doing them your IQ will suddenly shoot up !