A Couple of Dice Games

Here is how to find out for sure. . .
Get two dice.
a. Roll them at least 40 times altogether. Keep a record of the results for all the sums. (In a tally chart probably.)
b. How do your results compare with your prediction?
c. Draw a bar graph of your results.

Play the game at least two times to determine whether the game is fair or not.

WRITE-UP: Give a detailed explanation of how you KNOW the game is fair or unfair.