Xiaoli and Xiaohua want to decide who will take part in the calligraphy competition held in the city by touching the ball. The rules of the game are: put the numbers in an opaque bag.

first time

The second 2 3 4 52-(3,2) (4,2) (5,2) 3 (2,3)-(4,3) (5,3) 4 (2,4) (3,4)-(5,4) 5 (2. And the possibility of each result is the same. Among them, there are four results that the sum of numbers on two contact balls is even, namely (2, 4), (3, 5), (4, 2), (5, 3),

So the probability of Xiaoli's participation is 412 =13;

Method 2: Draw a tree diagram according to the meaning of the question as follows:

According to the tree diagram, there are 12 possible results * * *, and the possibility of each result is the same. Among them, there are four results of even numbers on the two contacted balls, namely (2, 4), (3, 5), (4, 2) and (5, 3).

So the probability of Xiaoli's participation is 412 =13;

(2) The game is unfair for the following reasons:

∵ The probability of Xiaoli participating in the competition is 13.

∴ The probability of Xiaohua participating in the competition is 1- 13=23.

∵ 13≠23,

This game is unfair.