Your answer would be "seeing is believing." The scientist was only telling the character about what the time traveling machine could do, but needed to actually show the character that the machine wasn't a fraud by actually sending it through time.
The question is incomplete. Based on the full question, it is statistical.
This is an excerpt from Stephen Levitt and Stephen Dubner's Freakonomics.
The excerpt gives the statistical data of the wrestlers. The win-loss percentage between 7-7 wrestlers and 8-6 wrestlers is judged when either one of them is in the bubble the next time.
There will not be pressure in the individual match. They win only 40% of the rematches.
