DC Energy Associate Power Trader interview questions

On campus interview. Interviewer is a trader with a technical background. He cared only if you answered a brainteaser right or wrong. I did not answer it right according to him, and left the interview with the belief that it was a communication problem. Given his description of the teaser, I nearly wanted to prove to him that there is no answer to his question. And I did about 10 questions asking clarifications, testing the bounds of the his question, etc during the interview, to no avail.