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Official Edexcel S3 thread Wednesday 20 May 2015 Morning [6691] watch

1. So we can all agree that question 5 was a huge pain in the rear end? How many people got it right?
2. Might as well start my life as a garbage man .
3. (Original post by Mufinator)
So we can all agree that question 5 was a huge pain in the rear end? How many people got it right?
lets hope <0.1% of candidates managed to get part D.
4. (Original post by TabulaSmaragdina)
69/75 a boundary, anything under that isnt justified tbh
stfu
5. (Original post by dhamm)
It was horrible, wasn't it! I went back to it at the end of the paper and luckily had a moment of inspiration to write U-bar as (U1+U2+...)/5.
I didn't really understand why though, in the previous parts I was clutching at straws so just said that the sample of 5 U's may not be independent.

Don't worry about it! Hardly anyone I've spoken to thought to rewrite U-bar like that. It was a very weird question.
Although I did get the same answer, I didn't use that method. Instead I simply subtracted the variances due to the dependence of the two samples and used that value. It did work but I'm wondering how many marks I would get?

I hate S3.
6. (Original post by Mufinator)
So we can all agree that question 5 was a huge pain in the rear end? How many people got it right?
I did, but by shear luck. Since the samples are dependent, I thought we should subtract the variances, though on the paper I simply did the calculation, but I did get the right answer in the end. Really worried now.
7. smashed that paper dno what you are all talking about, obviously you only ADD the variances when they are INDEPENDENT did non of you read your text book?!? Thanks for lowering the boundaries for 100 UMS,
8. (Original post by coder4)
Ended up getting question 5 by luck, terrible paper
Did you happen to subtract the variances?

9. (Original post by coder4)
Ended up getting question 5 by luck, terrible paper
Terrible all round or just q5?
For me everything but q5 went ok (mostly), had a mind blank. All 6 marks + 1 other mark lost for certain for part c and d.
10. How did people do the confidence interval question? Did you rearrange to find the standard deviation then do it with z being 1.6449 and n as 150
11. Can we make a poll?
On how we found it and expected A grade boundaries
I would, but school doesn't allow TSR

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12. For the difference of two means was it mu1-mu2-1.5? Or mu1-mu2=1.5?

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13. (Original post by coder4)
Ended up getting question 5 by luck, terrible paper
Looks like quite a few people got that correct then

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14. (Original post by dhamm)
I'll try and do a quick one now. I've got the numerical answers saved on my calculator so it shouldn't take very long!
omggg please do the unofficial with clear steps, I honestly think i failed!!
15. what was the expected freqs for the U[0,10] ??? i did them, but then i checked and they weren't adding up to 100 (i got 50, 30, 20, 10)
16. Here I was thinking I did everything else correctly but 5ii, and that I was still going to get a decent grade. Then I see that there was another page to Q6. Thanks Edexcel.
17. (Original post by MentalMath)
How did people do the confidence interval question? Did you rearrange to find the standard deviation then do it with z being 1.6449 and n as 150
Yes!

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18. (Original post by WildDevil96)
Here I was thinking I did everything else correctly but 5ii, and that I was still going to get a decent grade. Then I see that there was another page to Q6. Thanks Edexcel.
You missed that?!?
It was only...6? Marks

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19. (Original post by mmms95)
what was the expected freqs for the U[0,10] ??? i did them, but then i checked and they weren't adding up to 100 (i got 50, 30, 20, 10)
25 25 25 25
Uniform distribution

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20. (Original post by MentalMath)
How did people do the confidence interval question? Did you rearrange to find the standard deviation then do it with z being 1.6449 and n as 150
Yes finally some good news!

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