Combinatorics Q (2 Viewers)

[krypticlemonjuice]

How do we do c ii?


I don't understand this solution

 

[jimmysmith560]

Answering part (ii) involves using the answer you got from (i), which is 14!, as follows:

Let E be the event where Will, Mike, Dustin and Lucas are seated together.



I hope this helps!

 

[krypticlemonjuice]

Answering part (ii) involves using the answer you got from (i), which is 14!, as follows:

Let E be the event where Will, Mike, Dustin and Lucas are seated together.

View attachment 38882

I hope this helps!

Hmmm, but where did the (12-1)! come from?

 

[synthesisFR]

Hmmm, but where did the (12-1)! come from?

arrangements in a circle is (n-1)!

 

[fx82au]

Answering part (ii) involves using the answer you got from (i), which is 14!, as follows:

Let E be the event where Will, Mike, Dustin and Lucas are seated together.

View attachment 38882

I hope this helps!

dont act smart

 

[moonsuyoung]

Hmmm, but where did the (12-1)! come from?

Hi!
Because since Will, Mike, Dustin and Lucas have a condition (I think this is the right name for it) that they need to be all seated together. Treat this four people condition as one person so it's 11. I'm not too sure if that makes sense.

 

[Average Boreduser]

Hmmm, but where did the (12-1)! come from?

You're arranging around a circle. You are required to use one person as a reference point to arrange. this, therefore, means you will need to arrange by (n-1)!

 

[krypticlemonjuice]

You're arranging around a circle. You are required to use one person as a reference point to arrange. this, therefore, means you will need to arrange by (n-1)!

Hmmm, could you show your version of working for this q?

 

[Average Boreduser]

Hmmm, could you show your version of working for this q?

It would be exactly what jim has written down. This is more theory you will need to learn to beforehand to understand how to answer the qn. You should compare cases when you select a few people in a circular table. You'll notice that some cases overlap, which is compensated for by -ing 1 from the people you arrange (take one person as a reference).

 

[moonsuyoung]

It would be exactly what jim has written down. This is more theory you will need to learn to beforehand to understand how to answer the qn. You should compare cases when you select a few people in a circular table. You'll notice that some cases overlap, which is compensated for by -ing 1 from the people you arrange (take one person as a reference).

yaaa I'm pretty sure for this case it would be a "restriction" in perms and combs?

 

[Average Boreduser]

yaaa I'm pretty sure for this case it would be a "restriction" in perms and combs?

I think its just called circular arrangement (correct me if im wrong)

 

[moonsuyoung]

I think its just called circular arrangement (correct me if im wrong)

OH woopsies I read the question wrong

 

[carrotsss]

Hmmm, could you show your version of working for this q?

Whenever you do a circular combinatorics q, you always need to fix one person in place as a reference point, since otherwise you're including rotations of the circle which are actually the same.