(1) What is the basic number of events for throwing two dice? What is the probability that the sum of its points is 4? (2) Party A and Party B agree to work from 9 am to 12 am.

(1) has 36 basic events * * *, and the event "the sum of points is 4" includes: (1, 3),

(2, 2) and (3,1) * *, so its probability is: p = 336 =112;

(2) From 9: 00, let the arrival time of A be X, the arrival time of B be Y, and take point Q(x, y), then 0 < x < 3, 0 < y < 3.

The necessary and sufficient condition for two people is | x-y | < 1. As shown in the figure,

The probability is: p = 32? 2? 12? 2232=59