# AQA Statistics 1BWatch

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#1
How did you guys find the exam?
Should we try and make an unofficial mark scheme?
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3 years ago
#2
Yes but i don't remember my answers... Could you tell me your answers so that i could see something that might be familiar
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3 years ago
#3
What did you get for the claims ?
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3 years ago
#4
Okay im worried about the last Q. i used the standard error in the formula for condifence interval, my values for the confidence interval were all in the 300. When i used the S value given my confidence interval was from like 257 to 377 and this didnt seem right, too large and so i used the SE in my formula. I so forth got that the first claim was wrong as 400 euros was above the condidence interval ( which i converted into Euros ) as the highest value in the condience interval was 392 ( or something near to that) i got that the second claim was correct as 17.5% was less than 25%
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3 years ago
#5
the rest of the paper was okay tho, what are the grade boundary estimates as i need this to pull up my core 2!
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#6
I got 257 and 377 as well, but those were in £. So the confidence interval for Euros was 1.2 x those values. Thus 400 was in the confidence interval.
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3 years ago
#7
(Original post by sassmaster007)
I got 257 and 377 as well, but those were in £. So the confidence interval for Euros was 1.2 x those values. Thus 400 was in the confidence interval.
i got those values but they seemed too large and so i used the SE in the condidence intevral and got smaller values :/ which meant it was above the confidence interval when u x by 1.2. If you are right, i should get some of the marks tho i guess for working and then ECF for the claim i hope
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#8
What do you mean SE? Standard error?
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3 years ago
#9
(Original post by sassmaster007)
What do you mean SE? Standard error?
yes
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#10
(Original post by clairebear101)
yes
I believe that the confidence interval already uses standard error:

X +/- z X (s.d/sqrt n)

The standard deviation divided by square root on n is the standard error right?
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3 years ago
#11
(Original post by clairebear101)
yes
since we were using a mean of a sample i used the SE in the confidence interval formula where the s would go. Since this gave values closer to the mean, 253 and 377 seemed way to spread out for a 99% interval but i didnt know so hopefully should get method marks if i used the wrong values and then ECF for the claim.
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3 years ago
#12
Hi, what did eveyone do for the last probability question. i did over 500, then over 499 ect.
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3 years ago
#13
(Original post by sassmaster007)
I believe that the confidence interval already uses standard error:

X +/- z X (s.d/sqrt n)

The standard deviation divided by square root on n is the standard error right?
yes but i worked this out before and then replaced s.d with se but dw i probably got it wrong. It jsut seemed too large of an interval. It was 4 marks, so if i lost 1/2 there will i get ECF for my claim?
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3 years ago
#14
(Original post by douglaswill)
Hi, what did eveyone do for the last probability question. i did over 500, then over 499 ect.
nah this is wrong. I answer was 0.0308
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#15
(Original post by douglaswill)
Hi, what did eveyone do for the last probability question. i did over 500, then over 499 ect.
It said that the random picks were not from the sample of 500, so you just found out the probability from the random sample and times them together, without removing it.

0.296 x 0.296 x 0.294 x 0.294 = answer

Although I may be wrong
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3 years ago
#16
(Original post by douglaswill)
Hi, what did eveyone do for the last probability question. i did over 500, then over 499 ect.
Unfortuantely you weren't supposed to reduce the total by 1 each time, as the people selected were not from the sample, so you had to estimate from the sample.

Link to unofficial mark scheme is here:
http://www.thestudentroom.co.uk/show...1#post65559513
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3 years ago
#17
(Original post by sassmaster007)
It said that the random picks were not from the sample of 500, so you just found out the probability from the random sample and times them together, without removing it.

0.296 x 0.296 x 0.294 x 0.294 = answer

Although I may be wrong
u had to times this by 6 as there were 6 possible ways of arrnaging these probabilities
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#18
(Original post by clairebear101)
u had to times this by 6 as there were 6 possible ways of arrnaging these probabilities
Sorry yes you're right I forgot!
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3 years ago
#19
(Original post by clairebear101)
nah this is wrong. I answer was 0.0308
I think i got that answer which is strange. Well, apart from this question I think it was just the yellow and white thing which i might of got a couple of marks for, the condition where it said what the required questions and the confidence interval questions near the end which I might of got wrong. Overall not a bad paper, hopefully i got an A.
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3 years ago
#20
(Original post by Dapperblook22)
Unfortuantely you weren't supposed to reduce the total by 1 each time, as the people selected were not from the sample, so you had to estimate from the sample.

Link to unofficial mark scheme is here:
http://www.thestudentroom.co.uk/show...1#post65559513

How many marks do you think I could of got with doing this reduction?
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