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S1 Edexcel June 2008 help please!!

Hi,
I've been practicing this paper and I don't understand how to answer question 6a . The mark scheme answers it by using f(4)=1 but i don't understand why :s-smilie:

Can anyone help please?

The question paper

Mark Scheme

Thank You!
Reply 1
Because it's cumulative, the last box has to equal 1. 25/25=1 so (4+k)^2 must equal 25
Original post by Xara202
...


Since X can only take values for x=2,3,4. Then P(X<=4) = 1, but P(X<=4)= F(4), hence....
Reply 3
Original post by Naomiimoan
Because it's cumulative, the last box has to equal 1. 25/25=1 so (4+k)^2 must equal 25


Ah, I remember learning that but I completely forgot lol
Thank You :biggrin:
Reply 4
Original post by Xara202
Ah, I remember learning that but I completely forgot lol
Thank You :biggrin:


No probs :wink:
Reply 5
what the ef is a explanatory variable?
Reply 6
for 7c why do u times it by 3?
Reply 7
Original post by Xara202
Hi,
I've been practicing this paper and I don't understand how to answer question 6a . The mark scheme answers it by using f(4)=1 but i don't understand why :s-smilie:

Can anyone help please?

The question paper

Mark Scheme

Thank You!



can u help me answer q6 b? how do i do it?

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