There are 11 students in our Science class left to give their presentations. Today we will have time for 6 presentations. How many different ways can the teacher choose the presenters?

He has 2,772 ways

Step-by-step explanation:

Hello,

the teacher has to choose 6 students and there are 11 students in total.

When he chooses the first student he has 11 choices

if he has to choose 1 students he has 11 ways to do it

then for the second one he has 11-1=10 choices

if he has to choose 2 students he has (11*10) / 2 ways to do it (we do not count the duplicate - for instance if he chooses Steve and then Nils or Nils and then Steve this is only one group (Steve, Nils) we do not care of the order)

Then for the third student he has 10-1=9 choices

if he has to choose 3 students he has (11*10*9) / (2*3) ways to do it (we do not take into account the order of ppl in the group)

and so on and so forth

...

if he has to choose 6 students he has (11*10*9*8*7*6) / (2*3*4*5)

so he has 2,772 ways