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# Edexcel S3 - Wednesday 25th May AM 2016 watch

1. (Original post by Geraer1)
Yeah I was asking if in the first row the second value of probability is always 0.000? Sorry my question isnt really clear. See attachment
(Original post by connorbarr)
well i suppose Zacken can u explain lad
Yes, it should be.
2. (Original post by L'Evil Wolf)
How do you go about calculating unbiased estimate of variance from a frequency table.
retweet

EDIT: Never mind, realised what the question actually was
3. (Original post by L'Evil Wolf)
How do you go about calculating unbiased estimate of variance from a frequency table.
Same way that you would for a non-grouped data. Replace all the sum of x^2 or sum of x whatevs with sum of (x * frequency). It's S1 stuff, come on.
4. (Original post by Zacken)
Yes, it should be.
Okay thanks!
5. (Original post by Katiee224)
In what instances would we want to use the Central Limit Theorem? Like when does it come in handy?

Im worried i'm forgetting everything before the exam
CLT is used when you want to find the distribution of the sample mean.
6. Q6, PART a of 2013R,

The mean isn't it 17.2, which is the mean of the sample, instead of a+2 which is the populatiion mean?
7. (Original post by Zacken)
CLT is used when you want to find the distribution of the sample mean.
Gotcha

I feel like Will from the inbetweeners when he's revising for his exam and starts doubting eveything he knows
8. Which paper has a normal distribution goodness of fit test?
9. (Original post by Zacken)

That's a very good way to put it, hit it right on the nose!

Ah, nice nice. Did well in the stats modules, I'd wager? Those seem to be your forte.

Fairly confident for the FP's, not so much about Physics.
I find that stats the easiest branch of Maths and boring for a lot of people but it could be a lot worse. But yes, stats was probably my best exam

I suppose Physics needs actual work put in by you whereas the maths comes naturally
10. Can anyone please give some hard questions involving dice. Similar to ex3D basically.
11. Feel like I'm missing something here 6a on the June 14 IAL paper. Anyone fancy explaining it for me

Cheers
12. (Original post by ragreener1)
Feel like I'm missing something here 6a on the June 14 IAL paper. Anyone fancy explaining it for me

Cheers
Sum of (x * frequency) / (125 * 8), sin't it? What's confusing you?
13. (Original post by Geraer1)
Q6, PART a of 2013R,

The mean isn't it 17.2, which is the mean of the sample, instead of a+2 which is the populatiion mean?
The mean of the sample is 17.2 but the CLT says that the sampling mean is (normally) distributed with mean of the population.

(Original post by Katiee224)
Gotcha

I feel like Will from the inbetweeners when he's revising for his exam and starts doubting eveything he knows
Haha.

(Original post by AmarPatel98)
Which paper has a normal distribution goodness of fit test?
June 2013.
14. (Original post by Zacken)
Sum of (x * frequency) / (125 * 8), sin't it? What's confusing you?
How would you work it out if the value for '6 of more' was greater than 0?
15. (Original post by Zacken)
Sum of (x * frequency) / (125 * 8), sin't it? What's confusing you?
Of course, I don't know why I didn't get that. Like as soon as I posted it I was like oh yeah. Thanks mate
16. (Original post by Katiee224)
How would you work it out if the value for '6 of more' was greater than 0?
You wouldn't be able to, hence why they made it like that.

(Original post by ragreener1)
Of course, I don't know why I didn't get that. Like as soon as I posted it I was like oh yeah. Thanks mate
No problem.
17. (Original post by physicsmaths)
This is why edexcel are winning in life.
They have no clue what actual maths is.
So each individual thing is needed?
I write out the sum normally but not each value of each term n i use the other formula normally

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Yeah apparently. The utter inconsistency is the killer.

When we grow old we will make our own exam board, and it will be wonderful

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18. (Original post by Zacken)

June 2013.
cheers
19. S3 seems to be a popular module this year, weird.
20. (Original post by Zacken)
The mean of the sample is 17.2 but the CLT says that the sampling mean is (normally) distributed with mean of the population.
Oh I see thats why they said use CLT. Thanks!!

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