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# S1 - Permutations & Combinations help (OCR MEI) Watch

1. Hi! I'm taking S1 in January so that I can focus on C3 and C4, but my teacher's woeful and I've ended up having to teach myself. (Why did I take A2 maaaaths? As you can tell from my sig, it's not exactly relevant to my subject choice at uni :P)

How would I do this kind of question? (This way I can have a model answer to revise from!)

thank you!
2. (Original post by Mathematical)
Hi! I'm taking S1 in January so that I can focus on C3 and C4, but my teacher's woeful and I've ended up having to teach myself. (Why did I take A2 maaaaths? As you can tell from my sig, it's not exactly relevant to my subject choice at uni :P)

How would I do this kind of question? (This way I can have a model answer to revise from!)

thank you!
4i) 6P3
ii) (6P3)(7P4)(8P5)
iii) (6P3)(7P4)(8P5) / (21P12)
3. I see you have an offer for Oxford to read English Literature. What A-Levels have you taken?
4. (Original post by Physics Enemy)
4i) 6P3
ii) (6P3)(7P4)(8P5)
iii) (6P3)(7P4)(8P5) / (21P12)
Thanks for the answers--but seeing as I'm revising off this, what's your working and reasoning behind them? Sorry!
5. (Original post by Mr Inquisitive)
I see you have an offer for Oxford to read English Literature. What A-Levels have you taken?
I'm taking English, History, Maths and Spanish to A2
6. (Original post by Mathematical)
I'm taking English, History, Maths and Spanish to A2
Very good choices, I must say. I'll be applying next year to read PPE, but I'm not entirely sure what to take to A2...

Currently I'm studying English Literature, History, Maths, Economics & Politics AS.

- How was your Oxford interview? (if you don't mind me asking)
7. (Original post by Mathematical)
Thanks for the answers--but seeing as I'm revising off this, what's your working and reasoning behind them? Sorry!
Part 1 asks for the number of ways 3 Qs can be selected from 6. So that's 6P3.

Part 2 asks for all possible permutations of 3 from 6 Qs, 4 from 7 Qs and 5 from 8 Qs. 6P3, 7P4, 8P5 gives the individual number of permutations from 6, 7 and 8 Qs. Multiplying the 3 expressions gives you all such permutations.

Part 3 is probability; that also means the ratio of number of possible outcomes to number of total outcomes. Like P(6 on Dice) = 1/6, as there's 1 outcome from 6. Well there's 21 Qs and you need to choose 12; that's 21P12 total outcomes of 12 Qs from 21. Dividing your answer in Part 2 by 21P12 gives the required ratio.
8. (Original post by Physics Enemy)
Part 1 asks for the number of ways 3 Qs can be selected from 6. So that's 6P3.

Part 2 asks for all possible permutations of 3 from 6 Qs, 4 from 7 Qs and 5 from 8 Qs. 6P3, 7P4, 8P5 gives the individual number of permutations from 6, 7 and 8 Qs. Multiplying the 3 expressions gives you all such permutations.

Part 3 is probability; that also means the ratio of number of possible outcomes to number of total outcomes. Like P(6 on Dice) = 1/6, as there's 1 outcome from 6. Well there's 21 Qs and you need to choose 12; that's 21P12 total outcomes of 12 Qs from 21. Dividing your answer in Part 2 by 21P12 gives the required ratio.
Oh, thank you so much, you lifesaver!! <3
9. (Original post by Mr Inquisitive)
Very good choices, I must say. I'll be applying next year to read PPE, but I'm not entirely sure what to take to A2...

Currently I'm studying English Literature, History, Maths, Economics & Politics AS.

- How was your Oxford interview? (if you don't mind me asking)
PPE! Ouch, you're braver than me (I would totally have flopped Philosophy and Econ, and I'm too politically idealistic to pass any sort of politics exam ...)

If you can, take all of them to A2 (I couldn't choose what to--okay, that's a lie, I would have dropped maths from the first lesson of AS but having physicists for parents means maths is compulsory ) ... if not, keep english, because it's the best subject in the world. You could stand to lose History and, if you really struggle with it, Maths. But they're all awesome subjects and you seem like fantastically clever so no worries there

My interview was actually amazing. (APPLY TO ST ANNE'S IT IS LEGENDARY.) They asked me nothing on my PS (they asked me in the interview what subjects I was taking ...) and the second interview was just "so, what book have you just finished reading? tell me about it" and I talked for half an hour non stop. And you get a piece of poetry in the first interview and a piece of prose in the second and you're given 5 min to analyse it then you have chats with the interviewer about it ...

Nope, the really awful bit is the ELAT, omg. Is there an exam for PPE? WORRY ABOUT THAT BEFORE ANYTHING :/

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Updated: December 19, 2010
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