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Edexcel S2 - 27th June 2016 AM

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For E(A) I found what E(R) was, and also found what E(R^2) was but then for the answer I put 49pi... but I also wrote down the correct answer somewhere else on my page... how many marks will I lose ?
Reply 741
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wr123
1
Original post by Student1408
Thanks guys, i get it now :smile:


Ouch, I ended up doing E(A) = pi*(E(R))^2 :frown:
Original post by mangoli
Went alright but was nothing like the past papers. Got stuck on finding k for 20 minutes and decided to move on, how did you guys do it? I got k = 1/(a+21) and couldnt hew another equation in a from it


F(3)=1
F(2)=0

Then simultaneous



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Reply 743
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lara24
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I got k as 1/19 can someone please put up a solution I didn't know how to do it
Reply 744
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Yua
14
Original post by mangoli
Went alright but was nothing like the past papers. Got stuck on finding k for 20 minutes and decided to move on, how did you guys do it? I got k = 1/(a+21) and couldnt hew another equation in a from it


I done it by integrating and making it equal 1, so working out the area under the graph

then F(3) =1

then simultaneous
Someone explain why question 5 was 225
How did people get 225? I ended up solving the quadratic p^2 + 0.7p - 55.5 <0 something like that 🙈
I got n = 225 and 342.25 or something and i bsed a bit at the end to say it was 225 due to a positive sqrt being needed. I also wrote 225 is a whole number

How did you guys show that it was 225 and not 342.25?
Got k wrong (1/4? marks)
Got n for the 8 marker wrong (6/8? marks)
Got E(A) wrong (0/4 marks)

So I am thinking 65/75 or so, not what I wanted, hoping for low grade boundaries.
Original post by iMacJack
F(3)=1
F(2)=0

Then simultaneous



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You don't even need to do simultaneous equations 2a -24 = 0
For q3, wasn't it 49π? E(X)=5+9/2=7E(A)= πr^2= 49π
Original post by Student403
I got n = 225 and 342.25 or something and i bsed a bit at the end to say it was 225 due to a positive sqrt being needed. I also wrote 225 is a whole number

How did you guys show that it was 225 and not 342.25?


I just said that it had to be discrete and a whole number and put 225
Original post by lara24
I got k as 1/19 can someone please put up a solution I didn't know how to do it


I dont remember the numbers but you should have written F(2)=0 and F(3)=1.
With the first one k cancels so you can find a and sub it into the second to get k=1/9
(edited 7 years ago)
Original post by Student403
I got n = 225 and 342.25 or something and i bsed a bit at the end to say it was 225 due to a positive sqrt being needed. I also wrote 225 is a whole number

How did you guys show that it was 225 and not 342.25?


I put 342.25 as my final answer :frown:
I just hope there's a lot of method marks 🙃
looooooooool flopped that that was hard at least i got n=225 ;-; :frown:
Reply 756
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S14151
Can anyone remember the mark structure?
Reply 757
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apzoe
2
Guys what values did you get for a, b and k?
Original post by Music With Rocks
I put 342.25 as my final answer :frown:


I just put 225 in the whole thing and it worked out to get the probability they showed, my friend put both in when u find the z values, and said you get negative z for 342.25 i think? you didn't really have to say why you picked what?
Original post by NamelessPersona
I just said that it had to be discrete and a whole number and put 225


Oh okay nice

Original post by Music With Rocks
I put 342.25 as my final answer :frown:


342.25 would only have worked if you took the negative square root of it in the normal distribution expression which i considered but it seemed too specific

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