6,7,8,9, 10,;

12, 14, 16, 18,20;

18,2 1,24,27,30;

24,28,32,36,40;

30,35,40,45,50.

The possible situation of the product is as shown in the above figure, with duplication. Excluding duplicates (18, 24, 30), one * * *, there are 25-3=22 cases.

(2) The product is singular, (1) knows that there are six situations, so the possibility is 6 ÷ 25 = 0.24;

On the other hand, the probability that the product is a double number is1-0.24 = 0.76;

(3) According to (1), if the product is greater than 24, there is 1 1, and if the product is less than 4, there is no such thing as a small win, so the game is unfair.

(4) Game: Xiao Wang and Xiao Li each play 1 card and add up the numbers above. If the sum of numbers is singular, Wang Ying Jr.; If the sum of the numbers is even, Xiao Li wins. It is fair that both sides have a 50-50 chance to win this rule.