Professor Merle White of the mathematics department, Professor Leslie Black of the philosophy department, and young Jean Brown, who worked in the university's office of admissions, were lunching together.

"Isn't it remarkable," observed the lady, "that our last names are Black, Brown, and White and that one of us has black hair, one brown hair, and one white."

"It is indeed," replied the person with black hair, "and have you noticed that not one of us has hair that matches his or her name?"

"By golly, you're right!" exclaimed Professor White.

If the lady's hair isn't brown, what color is it?

That will depend upon what hair colour she chooses, but in this case I think it is currently white

Reasoning: we know her hair is not brown and she utters the first words, then being answered first of all by the person with black hair so we know this was not her. Thus white is the only remaining option.

Lex ... well done