Four cars, four seats.

1? Step: Arrange 4 drives A (4,4) = 24 at 4 locations.

The second one? Step: Put four ticket sellers in four positions A (4,4) = 24.

According to the principle of multiplication: * * has 24? =576 allocation schemes

2

The two points on the small circle and the big circle have the least number of straight lines.

When three groups of four-point lines appear at two points, the indirect method is adopted.

9 points determines the maximum number of straight lines: c (9,2) = 36.

The method of selecting 2 points from 4 points of every 1 group * * * line: c (4,2) = 6.

These six methods only correspond to 1 line, and there are five kinds of redundancy.

* * * There is 15 on the 4 o'clock * * * line in Group 3.

∴ These nine points can be connected into at least 36- 15=2 1 straight lines.

3 A = {1, 2,3} is obtained by the union of two subsets. How many of these Gemini sets are split?

{ 1,2} - { 1,3}; { 1,2} - {2,3}; { 1,3} - {2,3};

There are three kinds of Gemini divisions.