Obviously, your rate would be low. The implied domain of the question would throw people off. The question isn't a good indicator if someone can program.

Why don't you ask your manager the following.

If 1/2x +1/2(1/2x + 1/2(1/2x +1/2(1/2x + ... = y, then x = ?

If can't get it in 5 minutes, he is not fit for his job.