Four members from a 6-person committee are to be selected randomly to serve as chairperson, vice-chairperson, secretary, and treasurer. the first person selected is the chairperson; the second, the vice-chairperson; the third, the secretary; and the fourth, the treasurer. how many different leadership structures are possible?

We have arrange the four men from the six people
we note them with 1,2,3,4,5,6
We have to select 4 of 6 ( all combinations )
select 1,2,3,4 
these are the combinations
1234, 1243, 1324, 1342, 1423,1432,2134,2143,2314,2341,2413,2431,3124 ,3142, 3214,3241, 3412,3421, 4123,4132,4213,4231,4312,4321
24 combination for the first 4 members
Then select these:

1235 24 combination for these members
123624 combination for these members
124524 combination for these members
124624 combination for these members
125624 combination for these members
134524 combination for these members
1346...24 combination for these members
1356
1456
2345
2346
2356
2456
3456
the number is 3*4*5*6=15*24=360