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# AQA MS1B Wednesday 8th June 2016 Exam Discussion Thread watch

1. can someone help me with the wordy questions where you have to say something is valid or why something is not normally distributed etc :'(
2. (Original post by priyanka pandya)
can someone help me with the wordy questions where you have to say something is valid or why something is not normally distributed etc :'(
The validity is normally based on a confidence interval, in this circumstance compare the mean or the value given to the bounds of the confidence interval, if it falls within then you can accept the claim.

I'm not fully sure what you mean by something not being normally distributed but I'll say what I know. If the parent population is normally distributed then you can accept that your sample also is. If there is no parent population then if your sample is >30 you can say that you can use the Central Limit Theorem. I don't know when you would have to say something is not normally distributed but if there is an example I can try my best.

Hope this helps
3. (Original post by Hazzer98)
The validity is normally based on a confidence interval, in this circumstance compare the mean or the value given to the bounds of the confidence interval, if it falls within then you can accept the claim.

I'm not fully sure what you mean by something not being normally distributed but I'll say what I know. If the parent population is normally distributed then you can accept that your sample also is. If there is no parent population then if your sample is >30 you can say that you can use the Central Limit Theorem. I don't know when you would have to say something is not normally distributed but if there is an example I can try my best.

Hope this helps
thank you! and yes it does! i remember a question but i don't know which paper! do you have any tips to get full marks or very high marks for stats!
4. (Original post by priyanka pandya)
thank you! and yes it does! i remember a question but i don't know which paper! do you have any tips to get full marks or very high marks for stats!
I'd just advise getting used to the style of the questions, get familiar with the types/contexts of questions and their content, and just read the question very carefully as there is often important information in the wording.
I'll also say that I'm taking this as a retake in year 13 and am finding it a lot easier this year than I did last year (I also retook core 1 & 2, both of which were also easier) so don't worry too much if you think you'll have to retake it
5. (Original post by Nai18)
Makes sense. Thanks
Just to be sure, within 3 standard deviations, for your example is it
mean - 2/3 x standard deviations or is it

mean - 2 x standard deviations?

Posted from TSR Mobile
2*standard deviation or 3*standard deviation
6. (Original post by Hazzer98)
I'd just advise getting used to the style of the questions, get familiar with the types/contexts of questions and their content, and just read the question very carefully as there is often important information in the wording.
I'll also say that I'm taking this as a retake in year 13 and am finding it a lot easier this year than I did last year (I also retook core 1 & 2, both of which were also easier) so don't worry too much if you think you'll have to retake it
okay thank you
7. Goodluck everyone, I feel like I going to do really bad with this exam...
8. (Original post by Language student)
Goodluck everyone, I feel like I going to do really bad with this exam...
(Original post by Hazzer98)
I'd just advise getting used to the style of the questions, get familiar with the types/contexts of questions and their content, and just read the question very carefully as there is often important information in the wording.
I'll also say that I'm taking this as a retake in year 13 and am finding it a lot easier this year than I did last year (I also retook core 1 & 2, both of which were also easier) so don't worry too much if you think you'll have to retake it
(Original post by -jordan-)
2*standard deviation or 3*standard deviation
(Original post by priyanka pandya)
okay thank you
Anyone know what to do with the probablity questions where you calculate the probability and then they multiply the probability by 3 or some number for some reason. E.g.june 2015 question 3d). Need help fast
9. (Original post by fpmaniac)
Anyone know what to do with the probablity questions where you calculate the probability and then they multiply the probability by 3 or some number for some reason. E.g.june 2015 question 3d). Need help fast
For the probability of three events ABC all occurring there are six possible orders in which you can do it...So you multiple by six. If you're not sure consider it by drawing a tree diagram and see all the routes that you can take for it to be true. If you want two of the same events to occur and one different then there are 3 different combinations.
10. (Original post by -jordan-)
For the probability of three events ABC all occurring there are six possible orders in which you can do it...So you multiple by six. If you're not sure consider it by drawing a tree diagram and see all the routes that you can take for it to be true. If you want two of the same events to occur and one different then there are 3 different combinations.
I dont get it cos its going to be A and B and C anyways. So for the june 2015 question it didnt ask the order of it so it shouldnt matter should it. Im not sure how to draw a tree diagram for it can you give me an example pls.
11. (Original post by fpmaniac)
I dont get it cos its going to be A and B and C anyways. So for the june 2015 question it didnt ask the order of it so it shouldnt matter should it. Im not sure how to draw a tree diagram for it can you give me an example pls.
For example the ferry could arrive early on day 1, arrive on time on day 2, and arrive late on day 3. Or it could arrive on time on day 1, arrive early on day 2, and arrive late on day 3. You can carry on like that and arrive at 6 possible combinations.

The probability of each of those combinations occurring is exactly the same. But the question asks "Find the probability that, on these three days, the ferry arrives at port A early once,on time once and late once." - it doesn't specify what order it happens on those days. So the total probability of that happening is all of the probabilities added together, aka the probability of one combination multiplied by six.
12. Good luck everyone!!!
Hope you all get or come close to the marks you want tomorrow.
I am not a fan of the wordy stuff either.
13. Posting this to wish everyone a good luck tomorrow; try your best and we can discuss the exam afterwards
14. (Original post by -jordan-)
For example the ferry could arrive early on day 1, arrive on time on day 2, and arrive late on day 3. Or it could arrive on time on day 1, arrive early on day 2, and arrive late on day 3. You can carry on like that and arrive at 6 possible combinations.

The probability of each of those combinations occurring is exactly the same. But the question asks "Find the probability that, on these three days, the ferry arrives at port A early once,on time once and late once." - it doesn't specify what order it happens on those days. So the total probability of that happening is all of the probabilities added together, aka the probability of one combination multiplied by six.
Factorial usage?
15. (Original post by Dapperblook22)
Posting this to wish everyone a good luck tomorrow; try your best and we can discuss the exam afterwards
Seconded good luck to you too & to all of you
16. (Original post by xs4)
Factorial usage?
Yes although I'm pretty sure you only need to know when to use 3 or 6 for S1.
17. Very nice paper. Hopefully it will make up for my mess up on C2
18. (Original post by Andrew Dainty)
Very nice paper. Hopefully it will make up for my mess up on C2
19. Found this paper very difficult in comparison to C1 and C2, and in comparison to S1 past papers, rip

someone post unofficial markscheme pls
20. Ok i feel pretty confident about this paper but what did everyone else get for part iv of the Binomial question?? I got like 0.891 or something

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