That's simple to explain with a coin flipping analogy.

Chance means you get 5 guesses out of 10 coin flips right.

If 10 people guess the flip of 10 coins, how many of them will get more than 5 right?

Sure, there may be some who get 6, maybe 7 right, but that's not too far outside the normal distribution curve.

Galton board, anyone?

Brian