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# Ocr S1 27/01/10 watch

1. What did you think of it?

I thought it wasn't that bad, much easier than I expected it to be...
2. Finally someone made this, the only question I didn't know how to answer was the very final part of the last question (5 marks). Other than that it was fine.

Btw I've never covered sum to infinity with a Geometric distribution and it isn't mentioned in the specification ://

Do you think someone can get a mark scheme up here like they usually do (though I hear Mr M doesn't post S1 solutions, can't blame him really LOL).
3. (Original post by aki-o)
What did you think of it?

I thought it wasn't that bad, much easier than I expected it to be...

I don't see it anywhere
4. The Sum of a Geometric Series is a/(1-r)
In this case a = p²
r = q²
Since q = 1-p :
r = (1-p)²

Substitute into a/(1-r):

p²/(1-(1-p)²)

=p²/(1+1-p)(1-1+p)

=p²/(2-p)(p)

= p/(2-p)
5. I think that was alright, some parts on the second half of the paper were a bit confusing and then 9iii definitely haven't covered that in lessons.

EDIT: is in the formula book in the Pure Mathematics section
EDIT2: On the syllabus it's in the C2 section not S1
6. 8) For the Last part of the NEVER question, i found all the different ways of arranging it:

E _ E _ _
E _ _ E _
E _ _ _ E
_ E E _ _
_ E _ E _
_ E _ _ E

The Blanks are the letters N, V and R

There are 3! ways to arrange the Blanks, and there are six different situations so there are 6x3! Ways divide 60 ways in total:

This is 0.6
7. I thought it was pretty easy and I got the last 5 marker too.
8. (Original post by 729)
8) For the Last part of the NEVER question, i found all the different ways of arranging it:

E _ E _ _
E _ _ E _
E _ _ _ E
_ E E _ _
_ E _ E _
_ E _ _ E

The Blanks are the letters N, V and R

There are 3! ways to arrange the Blanks, and there are six different situations so there are 6x3! Ways divide 60 ways in total:

This is 0.6

This is what I got.

For the Jaguar question I got 15/23 x 39/53 for the second part.
9. I got 15/23 x 39/59, there were 60 in total right?
10. yeah there were 60 I got what you got 729
11. What was the jaguar question again?
12. probability that two randomly chosen people both have a jaguar given that the first one is female

i remember the number of females for jaguar was 15 and the other make was 8 or something, can't remember the numbers for the men although i think it was 25 and 12.. cant be sure

also is it allowed to assume a knowledge of C2...? cos no one in my class had done C2 yet, and geometric series is not in the spec for S1
13. (Original post by 729)
I got 15/23 x 39/59, there were 60 in total right?
It was a mistype I actually did get 59
14. Well, apparently the geometric series and sum to infinite was also on the june 2007 s1 paper. Damn my lack of past paper revision.
15. that last question was weird.
What do you think the grade boundaries will be like?
16. I thought that was horrible! The entire paper!
17. (Original post by butterz)
probability that two randomly chosen people both have a jaguar given that the first one is female

i remember the number of females for jaguar was 15 and the other make was 8 or something, can't remember the numbers for the men although i think it was 25 and 12.. cant be sure

also is it allowed to assume a knowledge of C2...? cos no one in my class had done C2 yet, and geometric series is not in the spec for S1
Yes, the specification states that S1 relies on C1 and C2 and students may be asked to apply some C1 and C2 knowledge to statistical problems. It is unusual for a question which does rely on C1/2 to actually come up though.
18. Wasn't the geo series formula in the formula booklet? I got that question right but I thought it was incredibly silly to not mention what 'a' and 'r' was for the benefit of those entered to do S1 early.
19. yeah. i havent done C2, i found the formula by chance since it wasnt in the prob & stats section, and i had no idea what to do with it... so i literally just wrote it. after half a page of useless scribbles before i chanced upon it
20. Yeah, the geo formula is in the formula book.

Overall quite an easy S1 paper I think

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