You are Here: Home >< Maths

# Edexcel S2 - 27th June 2016 AM

Announcements Posted on
Four hours left to win £100 of Amazon vouchers!! Don't miss out! Take our short survey to enter 24-10-2016
• View Poll Results: How did you find the Edexcel S2 exam?
Very hard
145
14.71%
Hard
331
33.57%
Normal
293
29.72%
Easy
152
15.42%
Very easy
65
6.59%

1. (Original post by economicss)
Please could someone explain question 7d on here https://57a324a1a586c5508d2813730734...%20Edexcel.pdf have never been able to understand it, thanks
Up to which point do you understand?

It starts with E(R) = E(aX^2 + bX) = aE(X^2) + bE(X) using laws of expectation.
2. (Original post by SeanFM)
Up to which point do you understand?

It starts with E(R) = E(aX^2 + bX) = aE(X^2) + bE(X) using laws of expectation.
Ah okay thank you, I understand how you find E(X) and Var(X) but I'm stuck from there, thanks
3. (Original post by economicss)
Ah okay thank you, I understand how you find E(X) and Var(X) but I'm stuck from there, thanks
So you know that (from my previous post) you are trying to find E(X^2) and E(X) and multiply them by a and b respectively and sum them to find E(R). And you know that, by the definition of Var(X), Var(X) = E(X^2) - E(X)^2, so E(X^2) = Var(X) + E(X)^2, and since you can work out those two things you can find E(R).
4. (Original post by SeanFM)
So you know that (from my previous post) you are trying to find E(X^2) and E(X) and multiply them by a and b respectively and sum them to find E(R). And you know that, by the definition of Var(X), Var(X) = E(X^2) - E(X)^2, so E(X^2) = Var(X) + E(X)^2, and since you can work out those two things you can find E(R).
Ah yes I see, thanks so much for your help!
5. Quite worried for this exam tbh
6. Does anyone know where I can find the s2 edexcel 2015 paper? I can't find the link to it anywhere. Thanks in advance!
7. (Original post by Zayniac)
Does anyone know where I can find the s2 edexcel 2015 paper? I can't find the link to it anywhere. Thanks in advance!
The edexcel website.
8. Hey, can someone help me?

Is it neccessary to learn the the proof for the E(X) and Var(X) for Continuous Uniform Distribution (Rectangular Distribution)?
9. (Original post by undercxver)
Hey, can someone help me?

Is it neccessary to learn the the proof for the E(X) and Var(X) for Continuous Uniform Distribution (Rectangular Distribution)?
Bad news: well, I've seen it pop up in a past paper once.

Good news: You don't need to remember it. It's essentially all in your formula book.

Can you see the bit in the "PDF is " thing? And then above that table is "Expectation/mean is " and the corresponding thing for ?

So all you need to do is, if you're asked to prove it, you don't need to remember anything. Open your formula booklet, they tell you the pdf is , they want you to find the E(X), okay then, just plug it into the formula given:

which you can finish up from here.

And they want variance, okay then, still just plugging in:

Where is just the expectation you found above.

For the expectation:
Spoiler:
Show

So
10. (Original post by Zacken)
Bad news: well, I've seen it pop up in a past paper once.

Good news: You don't need to remember it. It's essentially all in your formula book.

Can you see the bit in the "PDF is " thing? And then above that table is "Expectation/mean is " and the corresponding thing for ?

So all you need to do is, if you're asked to prove it, you don't need to remember anything. Open your formula booklet, they tell you the pdf is , they want you to find the E(X), okay then, just plug it into the formula given:

which you can finish up from here.

And they want variance, okay then, still just plugging in:

Where is just the expectation you found above.

For the expectation:
Spoiler:
Show

So

You're so quick lmao.
11. (Original post by undercxver)
Hey, can someone help me?

Is it neccessary to learn the the proof for the E(X) and Var(X) for Continuous Uniform Distribution (Rectangular Distribution)?
Learn... I'm not sure.

You can/should probably know how to get it by using definitions to find E(X^2) and E(X) and using that Var(X) = E(X^2) - E(X)^2, The one tiny bit that you need to know is that - that's the hardest bit and the rest is okay.

Hope you're finding everything okay
12. (Original post by undercxver)
Hey, can someone help me?

Is it neccessary to learn the the proof for the E(X) and Var(X) for Continuous Uniform Distribution (Rectangular Distribution)?
(Original post by Zacken)
Bad news: well, I've seen it pop up in a past paper once.

Good news: You don't need to remember it. It's essentially all in your formula book.
I think I may be screwed for S2.

I only know DRV + Estimation/sampling. Even then I only get 9/14 -> 10/15 marks on average.
Why does everyone say S2 is easy?
13. (Original post by XxKingSniprxX)
Why does everyone say S2 is easy?
Because it is?
14. (Original post by Zacken)
Because it is?
I feel so in S2. ... #feelsbadman

Not everyone is like you.

To reward myself I'll go do M1 revision, which I'm better at.
15. (Original post by SeanFM)
Learn... I'm not sure.

You can/should probably know how to get it by using definitions to find E(X^2) and E(X) and using that Var(X) = E(X^2) - E(X)^2, The one tiny bit that you need to know is that - that's the hardest bit and the rest is okay.

Hope you're finding everything okay
Yeah I understand that, I should be okay with it. Though I think I may panic if I see it in an exam though since it doesn't come up.

It's going alright. Thank you!

(Original post by XxKingSniprxX)
I think I may be screwed for S2.

I only know DRV + Estimation/sampling. Even then I only get 9/14 -> 10/15 marks on average.
Why does everyone say S2 is easy?
You will be fine! I was so pissed off at myself for leaving S2 revision till so late. But it's such a small module and easy to grasp. The ExamSolutions dude does a great job at explaining it. If you need any help for S2 feel free to ask me, it would be practise for me too.

Spend like a day on the other three topics you have left, and I promise you it will take you only a day to go over it all.
16. (Original post by undercxver)
You will be fine! I was so pissed off at myself for leaving S2 revision till so late. But it's such a small module and easy to grasp. The ExamSolutions dude does a great job at explaining it. If you need any help for S2 feel free to ask me, it would be practise for me too.

Spend like a day on the other three topics you have left, and I promise you it will take you only a day to go over it all.
I agree with that first bit ... disagree with the 2nd bit.

Thanks, will do. I'm spending next 3 days on learning it & then I'll start past papers for it. I'm just worried if I should put my eggs in 1 basket with M1 since Ik I'll score higher in that module than S2 or just try and juggle them both.

#struggleissurreal

Posted from TSR Mobile
18. (Original post by Bloom77)

Posted from TSR Mobile
What have you tried?
19. (Original post by Bloom77)

Posted from TSR Mobile
Seems like you're going to be doing simple unitary stuff. i.e. 1 customer in 6 minutes, so 10 customers in an hour. For the second part, think of a suitable approximation when a Poisson distribution becomes difficult to apply.
20. (Original post by Ayman!)
Seems like you're going to be doing simple unitary stuff. i.e. 1 customer in 6 minutes, so 10 customers in an hour. For the second part, think of a suitable approximation when a Poisson distribution becomes difficult to apply.
Omg I'm actually so stupid
I was using the 9 as my lamda value which is why I got confused
Silly me
Thank you!
Such an easy question as well lool

Posted from TSR Mobile

## Register

Thanks for posting! You just need to create an account in order to submit the post
1. this can't be left blank
2. this can't be left blank
3. this can't be left blank

6 characters or longer with both numbers and letters is safer

4. this can't be left empty
1. Oops, you need to agree to our Ts&Cs to register

Updated: August 20, 2016
TSR Support Team

We have a brilliant team of more than 60 Support Team members looking after discussions on The Student Room, helping to make it a fun, safe and useful place to hang out.

This forum is supported by:
Today on TSR

### Who is getting a uni offer this half term?

Find out which unis are hot off the mark here

Poll
Useful resources