nPr

[dekoyl]

Are things to do with examinable in units 3/4? I don't think I've had anything to do with it for the whole year and I can't remember how to use it at all.

I saw a few unit 1/2 questions here a few days a go and I didn't know how to do them

[trinon]

Are things to do with examinable in units 3/4? I don't think I've had anything to do with it for the whole year and I can't remember how to use it at all.

I saw a few unit 1/2 questions here a few days a go and I didn't know how to do them

No. That isn't actually on the 3+4 course and they can't test you on it. is however on the course.

[cobby]

you use nPr, when you want to take note of the order.

Example, in choosing between A,B,C,D & E , how many ways can you choose any 3 arranged letters. (This means ABC is different from ACB or BCA or...)
Then 5P3.


you use nCr , when the order is not important.

Example , how many ways can you get three letters from A,B,C,D & E. (here ABC is no different from BAC since you just got A&B&C.)
Then 5C3

[fredrick]

how would you use nCr to expand stuff like

[dekoyl]

PHEW. Thanks!
So stuff like "There are 10 chairs and there are 3 people: Bob, Tim and John. How many ways can they be seated if Tim and John can't sit together?" won't be examined on right?"

[cobby]

how would you use nCr to expand stuff like

you use nCr for that :| :| :| :S

[cobby]

PHEW. Thanks!
So stuff like "There are 10 chairs and there are 3 people: Bob, Tim and John. How many ways can they be seated if Tim and John can't sit together?" won't be needed right?

what do u mean by "wont be needed?"

[dekoyl]

what do u mean by "wont be needed?"

Fixed it Bad English.

I think I've got it now. Where arrangements matter = won't be tested on.

[cobby]

what do u mean by "wont be needed?"

Fixed it Bad English.

I think I've got it now. Where arrangements matter = won't be tested on.

i doubt it for 3/4 mm,
but i had a probability test y'day for 1/2 and nPr was on there..lucky i knew how to use it *wipes sweat of forehead*

[Mao]

Are things to do with examinable in units 3/4? I don't think I've had anything to do with it for the whole year and I can't remember how to use it at all.

I saw a few unit 1/2 questions here a few days a go and I didn't know how to do them

No. That isn't actually on the 3+4 course and they can't test you on it. is however on the course.

nCr is not really on the course either the application of pascal's triangle [nCr for lazy people], however, is.

[shinny]

I thought they've tested stuff from MM1/2 before though? Or is that only very very basic things like venn diagrams and such.

[ReVeL]

how would you use nCr to expand stuff like

Etc.

[Mao]

I thought they've tested stuff from MM1/2 before though? Or is that only very very basic things like venn diagrams and such.

yeah, mostly venn diagrams and very very simple sampling problems... like "if i have a bag of 5 red balls and 3 blue balls, what's the change of me drawing a red and a blue?" [use tree diagram]

[Captain]

I really hope nPr isn't on the exam, I've never done it before :/

Someone care to explain it, in context to a question? Thanks.

[dekoyl]

^It won't be on the exam.