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# Edexcel S2 - 27th June 2016 AM Watch

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1. (Original post by kosvengali)
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Could someone quickly explain to me how to solve 4c Jan 2013?
If -3 < X - 5 < 3 then a < X < b where a =... and b =....
2. (Original post by SeanFM)
Correct (though if you sketch the half of the distribution that you do know, it may help to..save some integrating, is all I will say).

Perhaps something is going wrong in the calculation or writing things down?
I've tried a lot here - can't seem to get an integer for K?
3. (Original post by iMacJack)
I've tried a lot here - can't seem to get an integer for K?
Working, please. Otherwise I'm not sure how to help. I wouldn't put it past me to have made a mistake in the question but I've checked a few times, so I'm not sure
4. (Original post by r3h4f)
I would have thought that it would be P(X<=8) because CR is X>=9?
can u explain how please? i dont get the entire question
5. Sorry i know this question has already been asked, but i just tried doing it myself and I'm a bit confused, its from June 2010.

Basically i worked out that:
2x+2y=20
and because your trying to find P(Y>6)
P(10-x>6) so therefore
P(X<4) = 1/2 but why isn't this the answer? why do you have to add on a 1/6 as the answer is 2/3 ??
6. (Original post by SeanFM)
Working, please. Otherwise I'm not sure how to help. I wouldn't put it past me to have made a mistake in the question but I've checked a few times, so I'm not sure
Here's my integration method

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7. how do you go about solving
d^4-8d^2+8=0

it was on the june 2014(r) paper
8. (Original post by Lilly1234567890)
how do you go about solving
d^4-8d^2+8=0

it was on the june 2014(r) paper
Substitute.

Let y = d^2
9. I dont get what theyve done in Q3b June 2013
10. I also dont get questions with Var like Var(3-2X)

E.g. If uniform dist. has intervals (b,4b) Find Var(3-2X)
11. (Original post by fpmaniac)
I also dont get questions with Var like Var(3-2X)

E.g. If uniform dist. has intervals (b,4b) Find Var(3-2X)
Var(3-2X) = 4Var(X)
12. anybody got links to jan 16 ial?
13. (Original post by fpmaniac)
I also dont get questions with Var like Var(3-2X)

E.g. If uniform dist. has intervals (b,4b) Find Var(3-2X)
Varx = 9b^2/12

var(3-2x) = 4Var(x) = 36b^2/12 = 3b^2?
14. (Original post by fpmaniac)
I also dont get questions with Var like Var(3-2X)

E.g. If uniform dist. has intervals (b,4b) Find Var(3-2X)
Did you do s1? Because you square the number in front of the X and times Var(X) by it. To work out VarX of a uniform distribution use the formula book
15. (Original post by fpmaniac)
I also dont get questions with Var like Var(3-2X)

E.g. If uniform dist. has intervals (b,4b) Find Var(3-2X)
a^2Var(X)

Then for continuouse uniform distribution Var(X)=((b-a)^2)/12

I think lol
16. (Original post by iMacJack)
Add five to both sides of the inequality and work it out? Take care of the 8 in the inequality though, as the maximum value is 6, so adjust the inequality taking note of this
Thank you!!? ^^

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17. (Original post by iMacJack)
Varx = 9b^2/12

var(3-2x) = 4Var(x) = 36b^2/12 = 3b^2?
(Original post by Dentistry101)
Did you do s1? Because you square the number in front of the X and times Var(X) by it. To work out VarX of a uniform distribution use the formula book
Thanks. And I didnt do S1

18. How do you do part (c) (d) and (e) ?
19. (Original post by SeanFM)
If -3 < X - 5 < 3 then a < X < b where a =... and b =....
Thank you

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20. (Original post by NotNotBatman)

How do you do part (c) (d) and (e) ?
How do you find R in terms of X?

(Hint: it is the area of a rectangle with one length being ... and the other ...)

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