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AQA Statistics 1B

How did you guys find the exam?
Should we try and make an unofficial mark scheme?
:smile:

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Yes but i don't remember my answers... Could you tell me your answers so that i could see something that might be familiar
What did you get for the claims ?
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%
the rest of the paper was okay tho, what are the grade boundary estimates as i need this to pull up my core 2!
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.
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
What do you mean SE? Standard error?
Original post by sassmaster007
What do you mean SE? Standard error?


yes
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?
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.
Hi, what did eveyone do for the last probability question. i did over 500, then over 499 ect.
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?
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
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
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/showthread.php?t=4150021&page=4&p=65559513&posted=1#post65559513
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
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!
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.
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/showthread.php?t=4150021&page=4&p=65559513&posted=1#post65559513



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

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