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# S3 Edexcel Central Limit Theorem Exercise 3D question 11 watch

1. Hey,

(Note that I understand the theory, this is just a question about why the inequality sign is that way round)

Okay so the complete question and answer is attached for reference

For part (b), shouldn't the inequality be < 1.96 rather than > 1.96?

Instead of using a mod, I just spelt it out as in between -10 and 10, and I keep getting < 1.96

Any help would be much appreciated!
Attached Images

2. (Original post by Nikhilm)
Hey,

(Note that I understand the theory, this is just a question about why the inequality sign is that way round)

Okay so the complete question and answer is attached for reference

For part (b), shouldn't the inequality be < 1.96 rather than > 1.96?

Instead of using a mod, I just spelt it out as in between -10 and 10, and I keep getting < 1.96

Any help would be much appreciated!
Attached Images

3. (Original post by Nikhilm)
TeeEm
If I follow the query correctly I also make it greater than 1.96
4. (Original post by TeeEm)
If I follow the query correctly I also make it greater than 1.96
Whenever your free, is it possible you could send your working out?
5. (Original post by Nikhilm)
Whenever your free, is it possible you could send your working out?
tomorrow evening I might do the question for you ... I finish work at 20.00
6. (Original post by TeeEm)
tomorrow evening I might do the question for you ... I finish work at 20.00
Thank you!
7. (Original post by TeeEm)
tomorrow evening I might do the question for you ... I finish work at 20.00
Bumppp
8. (Original post by Nikhilm)
Bumppp
will eat , catch up with the day, then I will do your question
9. (Original post by TeeEm)
will eat , catch up with the day, then I will do your question
Sweet!
10. (Original post by Nikhilm)
Sweet!
..
Attached Images

11. Thank you! How do I not get the same? (See last line)

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12. (Original post by Nikhilm)
Thank you! How do I not get the same? (See last line)

Posted from TSR Mobile
TeeEm
13. (Original post by Nikhilm)
TeeEm
there is no 1 - .... in part 2
14. (Original post by TeeEm)
there is no 1 - .... in part 2
Are you referring to

P(X < 10/n) is same as 1 - P(X > 10/n)

being incorrect?
15. (Original post by Nikhilm)
Are you referring to

P(X < 10/n) is same as 1 - P(X > 10/n)

being incorrect?
yes ... because the other side is fine as it is
16. (Original post by TeeEm)
yes ... because the other side is fine as it is
I'm sorry but I don't see how that isn't correct ... how'd you mean?
17. (Original post by TeeEm)
yes ... because the other side is fine as it is
I tried to get it into (P > x) form so that I could use a % table value
18. (Original post by Nikhilm)
I tried to get it into (P > x) form so that I could use a % table value
that is where you are wrong ... it is the other way round

Have a look at some simple inversions here
Attached Images
19. normal_distribution_calculations.pdf (851.1 KB, 59 views)
20. (Original post by TeeEm)
that is where you are wrong ... it is the other way round

Have a look at some simple inversions here
From the attachment, P(X < 110) = 0.9. I will call this value x

and P(X > 110) = 0.1. I will call this value y.

Hence, x = 1-y , i.e. P(X < 110) = 1 - P(X > 110)

Same thing I did for my answer no?
Attached Images

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