Statistics S1B 17/05/2013 Thread

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Reply 340

Gotzz

Original post by davidbaroi

is this edexcel? :confused:

No, AQA

Reply 341

Son234

This is the rest of my answers for 6a

Not entirely sure about the why the CLT not required is right for mine

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Reply 342

WheezyT

I have no idea what I did.....

Reply 343

Gotzz

Original post by Son234

This is the rest of my answers for 6a

Not entirely sure about the why the CLT not required is right for mine

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

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

Reply 344

emilymw

Did anyone put the unbiased estimate of standard deviation, 17.5 i think, for for the first part of question 1???? :confused:

Reply 345

the_googly

I got 27 for the last part of question 3.

Reply 346

Son234

Original post by Gotzz

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

It says on the question modelled by a normal random variable

That's why I didn't put it was normally distributed

And CLT is only valid for n>30 big large sample size

So to me it made sense to use 25 ==> n<30

It was 1 Mark too so I'm not that bothered

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Reply 347

Joe899

Original post by the_googly

I got 27 for the last part of question 3.

So did I!

Reply 348

Gotzz

Original post by Son234

Okay I'm not too sure then. It was just that I remember doing some a similar question in a past paper and it said that and didn't allow the sample size point.
Maybe you're right.

Reply 349

002

Was it 27 or 14 for the last part of Question 3?

Reply 350

Gotzz

Original post by 002

Was it 27 or 14 for the last part of Question 3?

Reply 351

the_googly

Anybody want to the whole paper and upload it like somebody did with C1 and C2? :-)

Reply 352

002

Original post by Gotzz

Why?

Reply 353

MrJiggly

Original post by Son234

Normal random variables are distributed normally. You just had to say that it is known that it is normally distributed so CLT is unecessary.

I'm not sure whether you'll get a mark for saying 25 is smaller than 30, so it's not valid. Technically, 25 is an acceptable sample size.

Reply 354

Gotzz

Original post by 002

Why?

0.85 - 0.175 = 0.675
0.675 x 40 = 27

Reply 355

Gotzz

Original post by MrJiggly

Would you have to specifically say "it is known"? Or do you think saying it is normally distributed is enough?

Reply 356

MrJiggly

Original post by Gotzz

Would you have to specifically say "it is known"? Or do you think saying it is normally distributed is enough?

Probably just have to mention the words : "Normally distributed"...

at least I hope so... :tongue:

Reply 357

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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Reply 358

Gotzz

Original post by MrJiggly

Probably just have to mention the words : "Normally distributed"...

at least I hope so... :tongue:

Me too!

Reply 359

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.