In his defense (don't ask me why I'm defending him, I don't !@#$ing know), 115 would be 1.5 standard deviations away from the mean, which would mean he's safely selecting from within the "gifted" category.
Which doesn't explain why he picked a standard deviation of 10 and a selection criteria of 115 out of his ass, rather than go with the standard 30 and 145 in a normal IQ measure. It's not really material to the math, since a gaussian's a gaussian's a gaussian...but it's pretty funny that, when attempting to measure something related to IQ, he can't even pick the correct numbers to describe it.