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# Ocr mei statistics 1 exam thread (24/05/13) Watch

1. (Original post by jo7777)
Hey guys wondering if someone would explain something to me?
I really struggle with probability :P

On question 4 of this paper:
http://www.mei.org.uk/files/papers/s110 ju_wtfd.pdf
Why is the answer for i) 1 x 1/5
I thought it would be 1/5 x 1/5 ???
This is because from the first pack he opens he is guaranteed to get a fridge magnet or whatever so the probablity is 1 after that the probablity that he gets the same magnet will be 1/5. So the probablity therefore is 1 x 1/5 if you get what i mean
2. (Original post by blackstarz)
This is because from the first pack he opens he is guaranteed to get a fridge magnet or whatever so the probablity is 1 after that the probablity that he gets the same magnet will be 1/5. So the probablity therefore is 1 x 1/5 if you get what i mean
Yep makes perfect sense, thanks +rep
3. Get all the pure statisitcs stuff - absolutely hate the worded questions with worse answer -e.g what happens to the mean etc a anyone the same ?

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4. (Original post by krishkmistry)
Get all the pure statisitcs stuff - absolutely hate the worded questions with worse answer -e.g what happens to the mean etc a anyone the same ?

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Yep, exactly! I dropped English for a reason!!

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5. Anyone know what measures of central tendency are ?

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6. When doing binomial distributions when is the best time to use the table they give you, and when is the best time to do it with the ncr method?
7. (Original post by Tinglay)
When doing binomial distributions when is the best time to use the table they give you, and when is the best time to do it with the ncr method?
I use the tables when in the question they mention "at least" but if they ask for an exact probablity for example "what is the probability that he picks exactly 4 sweets" then id use the ncr method.
8. Can someone explain how you calculate standard deviation? But dumb it down for me

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9. (Original post by krishkmistry)
Anyone know what measures of central tendency are ?

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The mean mode and median
10. i'm really hoping this exam goes well after that horrible core 2 paper

can anyone give me a sort of step to step guide for hypothesis testing both 1 and 2 tail i can never get them right and they are worth so many marks when they come up, thanks
11. (Original post by amyb96)
i'm really hoping this exam goes well after that horrible core 2 paper

can anyone give me a sort of step to step guide for hypothesis testing both 1 and 2 tail i can never get them right and they are worth so many marks when they come up, thanks
two tailed

http://www.examsolutions.net/maths-r.../example-5.php

one tailed is on the s1 section of examsolutions.

Its paper June 2008 and question 7iiib, I just have no idea how to do it! Thanks
13. (Original post by jo7777)
Hey guys wondering if someone would explain something to me?
I really struggle with probability :P

On question 4 of this paper:
http://www.mei.org.uk/files/papers/s110ju_wtfd.pdf
Why is the answer for i) 1 x 1/5
I thought it would be 1/5 x 1/5 ???
I remember that question! I got confused as well but if you think about it, it actually makes sense. The probability of getting a magnet in the first cereal is 1, as you have none of the magnets and each cereal must have a magnet.

Then the second cereal that Keith buys, there are 5 magnets that she can get. She has 1 of those 5 so the probability of getting the same one is 1/5.
14. (Original post by Tinglay)
What's everyone's revision plan for s1?

I'm using ExamSolutions for each topic as I do past papers topic by topic

http://vle.woodhouse.ac.uk/topicdocs...anMrDobson.pdf

A plan made by a teacher at my school if anyone needs it. I think it's useful if you want to save doing whole past papers until a few days until the exam.
How does that plan work?
15. (Original post by Saif95)
How does that plan work?
Instead of working through whole papers, you work through types of questions in each past paper. I don't recommend doing this now since it's too late. Only do it if you're really unfamiliar with a topic.
16. Are we given formulas in the formula booklet?
17. When finding the median how do you know whether its n/2 or n+1/2?? Is it to do with grouped data?
18. (Original post by DarkWillow)
When finding the median how do you know whether its n/2 or n+1/2?? Is it to do with grouped data?
we got told that if the number is over 50, you don't have to add the one, you can just divide by 2 straight away. However, our teachers said last year, there was a median question and the number was below 50 so nobody added the one but they lost a mark because of that. So,...always use n+1/2 for the median, no matter how big or small the number is
19. when the hypothesis test is two tailed, you half the significance level don't you?
and also, how can you tell if it's meant to be two tailed or not because your hypotheses depend on it being two or one tailed so confused
20. Hey, wondering if someone could help me?

(( It's about question 7)v of this paper: http://www.mei.org.uk/files/papers/2012_Jan_s1.pdf
The weight of the largest Welsh Mountain lamb was originally recorded as 6.5 kg, but then corrected.
If this error had not been corrected, how would this have affected your answers to part (iv) ))

So basically it says the median would be unchanged... and so would the IQR...
Surely if the upper range increases, then both the median and iqr would also increase?!

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