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Statistics S1B 17/05/2013 Thread

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Reply 360
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.


The question before it had a different probability...
3 a (iv): "at least their reserve prices but not their lower price estimates" p=0.35
3 b: "at least their reserve prices but not their upper price estimates" p=0.675
(edited 10 years ago)
Reply 361
Original post by Son234
Here's my exact answers to question 3

I can categorically say the answer to part b in question 3 is 27 not 14 :frown:

I lost 2 marks but i have shown the answer anyway


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yup, got that :smile:

Is it confirmed that it is 27 and not 28 like a couple other people said?

I did hardly any working as I used the graphical calculator...I'm just hoping I haven't made any silly mistakes.
Reply 362
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.


My answer was 14 -_-


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Reply 363
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 was 27. Your claim relies on the fact that the above events were mutually exclusive, but they weren't.
An antique could fall into more than one category (e.g. Sold above reserve, sold above lower estimate). So yes, the probabilities did add up to more than one, but that's indifferent.
Reply 364
Original post by SamuelJ
It was 27. Your claim relies on the fact that the above events were mutually exclusive, but they weren't.
An antique could fall into more than one category (e.g. Sold above reserve, sold above lower estimate). So yes, the probabilities did add up to more than one, but that's indifferent.


I don't know about you guys, but I'm trusting the wise words of Samuel Jackson

Original post by Gotzz
I think for the CLT, all we had to say was that it was a normal distribution.


I put that the sample size was small i.e. n<30
So the central limit theorem didn't apply. But there was one past paper I did that didn't accept sample size as a reason :s-smilie:
Reply 366
Original post by MrJiggly
I don't know about you guys, but I'm trusting the wise words of Samuel Jackson



It's definitely 27.
Yay if it is 27 lol
How do you question 2b and 2c?
Reply 369
Original post by the_googly
How do you question 2b and 2c?


find the corresponding z value for 0.98, then use the standardising equation.
And for part c, you find the z value for 0.99 (1-0.01) and put a minus sign in front of it, and then use the standardising equation again.
Reply 370
Here's my exact answers to question 2

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


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Reply 371
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 :smile:


This was posted from The Student Room's iPhone/iPad App


For part c, I used the negative z value. Because I thought it didn't make sense for the probability of X<410 to be only 0.01 if the mean is 403.
So the value I got was around 417.
Original post by EmilyC96
Venn diagram? :s-smilie:


I think he Must be talking about other paper with coursework SS1A or wrong exam board.
So.... last question

"each bag"... I went with that meaning "all"... but I didn't know?
Reply 374
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 :smile:


This was posted from The Student Room's iPhone/iPad App


Exactly the same as me!
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 :smile:


This was posted from The Student Room's iPhone/iPad App


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...
Reply 376
Original post by Gotzz
For part c, I used the negative z value. Because I thought it didn't make sense for the probability of X<410 to be only 0.01 if the mean is 403.
So the value I got was around 417.


I used the negative z value as well. Can't remember exactly the answer though...lemme quickly check.
Reply 377
Original post by steviep14
So.... last question

"each bag"... I went with that meaning "all"... but I didn't know?


I get what people mean by the last question haivng to be to the power of 10 for 4 marks, however the questions states 'weight of the cement in EACH of the 10 bags@ surely the word each would mean that you would just use normal distribution?
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 :smile:


This was posted from The Student Room's iPhone/iPad App


Meh can't remember what I did but probably lost all the marks for b and c
Unofficial mark scheme anywhere for this? :smile:

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