Puzzle

The answer is 50.

1 person out of a hundred is 1% (right handed). The right handed single person must stay.

1 person out of 50 is 2%, meaning 50 fewer left handers in the room.

Of course, it has to be doable, and the answer cannot be silly, like 42.7 people, so you could make some kind of a guess even if you had no clue.

I gather the contestant did not.