[disgruntledphd2]

That's a very good point, especially given that the standard deviation of IQ scores is 15, which suggests that scores of between 125 and 140 are possible (indeed, somewhat likely) for the same individual - a finding which I have found in my own experience of taking them.

Additionally, IQ tests were developed to assess someone's ability to benefit from formal education, and to the extent that these skills are uncorrelated with successful outcomes, IQ will be a poor predictor of it.