http://en.wikipedia.org/wiki/Dunning-Kruger_effect The results of the Dunning-Kruger study show that incompetent people massively overestimate their ability, while truly competent people are typically unaware that they are on the far-right side of the bell curve. Assuming that the interviewer is aware of this effect, the best strategy to play is modesty.

Yes, at-least by the standards of the people I worked and studied with in the past.

It depends on how do you definition and measure smart? In looking at my employment history and referencing my level of education along with my accomplishments, I'm confident I've meet your prerequisites and exceptions for this job. I am smart enough to know that there's always more to be learned.

Smart is a relative term. But I’d like to think I’m good at solving problems other people are afraid to take.

i am delicate balance of confidence and humility, lets put it that way

i'm f**** smart