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# Statistics S1B 17/05/2013 Thread Watch

1. (Original post by steviep14)
403 can not be the mean... think about it... P(<410) = 0.01 can only be to the left of the mean... you needed to use -2.3263.. which gave 417...
Yes, that's what I did, and that was my logic
2. (Original post by MrJiggly)
I used the negative z value as well. Can't remember exactly the answer though...lemme quickly check.
Yay. I used positive first then realised it doesn't really make sense and changed it
3. Also with regards to "each"... you would not get 4 marks for just normal distribution... it is a 3 mark question which would suggest, mark 4 is for "to the power 10"
4. (Original post by steviep14)
403 can not be the mean... think about it... P(<410) = 0.01 can only be to the left of the mean... you needed to use -2.3263.. which gave 417...
When I subbed the 403 back in the values seemed to fit

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5. (Original post by AMELIA-x)
When I subbed the 403 back in the values seemed to fit

Posted from TSR Mobile
Draw a graph... you cannot have Y(<410) with a value less than 0.5 unless the 410 is to the left of the mean.. it is just not possible

with a mean of 403, 410 is to the right of the mean... it isn't actually possible to do
6. (Original post by Gotzz)
Yay. I used positive first then realised it doesn't really make sense and changed it
yup, it is 417. Drawing the graph makes it easier to see. Funnily enough, I hate drawing graphs and my stats teacher kept having a go at me for not doing so. Lucky I drew it today XD
7. (Original post by steviep14)
403 can not be the mean... think about it... P(<410) = 0.01 can only be to the left of the mean... you needed to use -2.3263.. which gave 417...
OMFG YES, this is what I did! I love you.
8. (Original post by 002)
How can the answer to the last part of the question possibly be 27?! If it was 27, the probability used would be 0.675. With this probability, is would have been impossible to answer the binomial distribution question which went before it, as 0.675 is not on the binomial tables, whereas 0.35 is (0.35 x 40= 14). Sorry to break it to you guys, but 14 is clearly the correct answer to the last part of question 3.

Teacher told us it was 27
9. Q1

Mean = 62.3
SD = (Forgotten it)

b) Mean = 16.8C
SD = 5/9 x (whatever it was)

r = 0.99(7)
Linear Scaling has no effect on PMCC (oe)
10. (Original post by steviep14)
Draw a graph... you cannot have Y(<410) with a value less than 0.5 unless the 410 is to the left of the mean.. it is just not possible

with a mean of 403, 410 is to the right of the mean... it isn't actually possible to do
Aw bad times for me oh well hopefully I get some marks for working!

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11. (Original post by 002)
How can the answer to the last part of the question possibly be 27?! If it was 27, the probability used would be 0.675. With this probability, is would have been impossible to answer the binomial distribution question which went before it, as 0.675 is not on the binomial tables, whereas 0.35 is (0.35 x 40= 14). Sorry to break it to you guys, but 14 is clearly the correct answer to the last part of question 3.
It's 27, you don't need to use the tables, it's just 0.675*40, which is why the question asked what is the expected number of whatever, hence no tables are needed.
12. (Original post by AMELIA-x)
Aw bad times for me oh well hopefully I get some marks for working!

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Well.. at least 2/4 I'd think... you set the formula out, and you found 2.3263, just didn't finish it correctly..
13. Was probably one of the easier S1B papers I can think of
A 61
B 55
C 49
D 43
E 37
14. Could anyone confirm that the equation of the regression line was y= 0.46 + 1(x) a lot of people got 0.6/0.66 is anyone quite certain as to what it should be?

Also for the very last question i did everything right but when standardising divided 0.35 (the standard deviation) by square root of 10, will that cost me 3 marks?
15. the regression equation question annoyed me idk how you're suppose to do it without numbers : (
16. (Original post by Room4student)
Could anyone confirm that the equation of the regression line was y= 0.46 + 1(x) a lot of people got 0.6/0.66 is anyone quite certain as to what it should be?

Also for the very last question i did everything right but when standardising divided 0.35 (the standard deviation) by square root of 10, will that cost me 3 marks?
It is y = 0.46 + 1.001x
people who got 0.60 are going to lose 1/2 marks because they rounded... you should never round early...

As for the second question, unfortunately, you're likely to lose a couple... but maybe not 3..
17. (Original post by Son234)
Here's my exact answers to question 2

I think they are all right but correct me if I'm wrong

This was posted from The Student Room's iPhone/iPad App
Will I get any marks for not finding the value of Z?
18. (Original post by steviep14)
Was probably one of the easier S1B papers I can think of
A 61
B 55
C 49
D 43
E 37
Don't say that :-(
19. (Original post by the_googly)
Don't say that :-(
There was nothing "challenging" in comparison to other papers... the last 8 marks were tough... but really, it wasn't horrific.. okay, the regression was nastier than previous years, but still...
20. (Original post by steviep14)
It is y = 0.46 + 1.001x
people who got 0.60 are going to lose 1/2 marks because they rounded... you should never round early...

As for the second question, unfortunately, you're likely to lose a couple... but maybe not 3..
thanks, do you remember any of your answers for the probability question.. david and alison ones?

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