I would divide the 18000 by 13.26 to get the number of hours needed.
18000/13.26~169.7 days with 8 hour shifts.
4 tables = 1 group. So in 10 groups of tables, there are 40 tables. Each table seats 8 students, so you multiply 8 by 40, and that leaves your answer as 320 students. :)
<span>Number of flowers = 6
Number of flowers to choose = 3
We need to solve it using permutations:
6!/3!=1*2*3*4*5*6/1*2*3 = 720/6 = 120
The answer is: there are 120 different arrangements using 3 types of flowers out of 6 types available</span>
