27!
6 ways. 3 x 2 x 1 = 6
Yes. There can be a line perpendicular to the given line at every point on it, and you know how many different points there are on it ...
720
20*19*18*17*16 = 1860480 ways.
19*18*17*16*15 = 1,395,360
420
3 items (or people) can line up in 6 different sequences. 6 items (or people) can line up in 720 different sequences.
36
120
120
If the people are always facing forward? 24 ways.
There are n! (n factorial) ways that n people can stand in line. So six people can stand in line in: 1*2*3*4*5*6 = 720 different ways
only three first class second class third class
284 Second-Class people sailed Titanic.
Assuming you mean the order in which they stand in a line, this is simple combination of three from three, and there are six possible combinations:ABCACBBACBCACABCBA
There are a great many different things that could be considered the class. The class could be considered a group of children.
There were 3 classes on the RMS Titanic, first class was for the richest people, second class was for the at least rich people and third class was for the poorest people.