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# S1 questions help

Maths and statistics discussion, revision, exam and homework help.

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1. S1 questions help
can someone explain how i do part b of this question (In attachment)

i thought u do 1 x k + 2 x k + 3 x k

but if i do this i get the wrong answer.... how do i do it.

thanks
Attached Thumbnails

2. Re: S1 questions help
You realise that it says

so instead of 1, 2, 3 ... you use?????

Last edited by TenOfThem; 09-05-2012 at 22:51.
3. Re: S1 questions help
(Original post by TenOfThem)
You realise that it says

so instead of 1, 2, 3 ... you use?????
1,4,9

i tried This gives 1 and that is not the answer
Last edited by 95_alim; 09-05-2012 at 22:22.
4. Re: S1 questions help
(Original post by 95_alim)
1,4,9

i tried This gives 1 and that is not the answer
yes it is
5. Re: S1 questions help
(Original post by 95_alim)
1,4,9

i tried This gives 1 and that is not the answer
Is the answer to part (b) 9/14 ?
6. Re: S1 questions help
(Original post by raheem94)
Is the answer to part (b) 9/14 ?
No

Did you miss the =
7. Re: S1 questions help
It's X greater than or equal to 2. 1 isn't greater than or equal to 2.
8. Re: S1 questions help
(Original post by TenOfThem)
No

Did you miss the =
I did miss the equal to.

Won't it be done in this way,

Am i right?
9. Re: S1 questions help
(Original post by raheem94)
I did miss the equal to.

Won't it be done in this way,

Am i right?
yes
10. Re: S1 questions help
(Original post by TenOfThem)
yes
Actually the 'equal to' was very difficult to read so i missed it.

Why were you saying that the answer is 1?
11. Re: S1 questions help
(Original post by raheem94)
Actually the 'equal to' was very difficult to read so i missed it.

Why were you saying that the answer is 1?
I was saying that showing (1+4+9) * 1/14 = 1 showed that k=1/14

It may have been better to say (1+4+9)k = 1 => k=1/14 but the requirement was only show
12. Re: S1 questions help
(Original post by TenOfThem)
I was saying that showing (1+4+9) * 1/14 = 1 showed that k=1/14

It may have been better to say (1+4+9)k = 1 => k=1/14 but the requirement was only show
I was confused because in the 1st post, the OP is asking for help in part (B).
13. Re: S1 questions help
(Original post by raheem94)
I was confused because in the 1st post, the OP is asking for help in part (B).
I guess I missed that
14. Re: S1 questions help
(Original post by TenOfThem)
I guess I missed that
yep figured out b) but need help on C
15. Re: S1 questions help
(Original post by 95_alim)
yep figured out b) but need help on C
What is the rule for E(X)
16. Re: S1 questions help
how do i do c? thats what i was asking about really sorry for the error
17. Re: S1 questions help
(Original post by TenOfThem)
What is the rule for E(X)
1 * k + 2 *k + 3 * k
18. Re: S1 questions help
(Original post by 95_alim)
1 * k + 2 *k + 3 * k
no it is SUM[xP(x)]
Last edited by TenOfThem; 09-05-2012 at 23:12.
19. Re: S1 questions help
(Original post by 95_alim)
how do i do c? thats what i was asking about really sorry for the error
Don't mind, but have you read the chapter from the book?
20. Re: S1 questions help
(Original post by raheem94)
Don't mind, but have you read the chapter from the book?
yes have read the chapter.. can do all other questions of E(X) but struggling with this one?

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Last updated: May 9, 2012
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