Let the length of the two sections to be cut be x and y meters, then x+y=4, and now x "0.5 and y" 0.5 are needed. Then, in the rectangular coordinate system, the part of the line segment y = 4-X (Y "0, X" 0) satisfying X "0.5 and Y" 0.5 is painted red, and its length is calculated and divided by the line segment Y = 4.

We call it classical probability (this is called geometric probability, and there is a common problem called dating problem) because when we finally calculate, we divide the possible situation (here is the red part) by the total situation (here is the line segment Y = 4-X (Y "0, X" 0)), which conforms to the basic characteristics of classical probability.