Solution: p = (C52)/(c103) =112.
Analysis: There are 10 users for the first time, and the number of users is 1- 10. Choose 3 people at random. Method 1 * * has (C 10 3), and the maximum number is 5, that is to say, 5 must be drawn, and the other two should be drawn in the middle of 1-4. The number of ***4 in 1-4 is calculated in a combined way, not in order.
Solution: p = (C42)/(c103) =1/20.
Note: (C5 2) is the number of written combinations, with C on the left, 5 on the lower right and 2 on the upper right.