Test and analysis: (1) list or tree diagram to get all equal possible situations, find out the situation that the sum of the numbers is even, and find out the probability of Xiaoli participating in the competition; (2) Calculate the probability of Xiaohua's participation from the probability of Xiaoli's participation, and compare whether the game is fair.
Problem analysis: (1) Draw a tree diagram according to the meaning of the problem as follows:
∫ As can be seen from the tree diagram, there are 12 equal possible results * *, and there are four results in which the sum of numbers on two contact balls is even, namely (2,4), (3,5), (4,2) and (5,3).
∴: The probability of Xiao Li participating in the competition is.
(2) The game is unfair for the following reasons:
∫ Xiaoli's entry probability is, and Xiaohua's entry probability is 1 =.
This game is not fair.