Edexcel S2 - 27th June 2016 AM

Edexcel D2 is on Wednesday :'(

a. b = 23/6

b. k = 2

c E(X) = 1.39. E(X^2) = 2.70. Var(X) = 0.77. Deviation = 0.88 (answers within that range, depending on rounding etc)

d. IQR question removed - takes too much time.

e. 0.69.






Well done the last bit should be 2 s.f but doesn't matter really. Just something to be wary of in the exam if they specify how many s.f you need.

Oh snap I feel sorry for you I thought I was unlucky with S2!

Afraid not - k is a whole number - actually, let me double check that. I think I've messed it up

Yes - k should be a whole number. Phew.

Should be closest. Please post a link to the paper



Correct. The binomial distribution (a discrete one) takes no values between 6 and 6.9, so those two things are equivalent.

I'm not too stressed thanks to doing well in AS papers, but I also have Physics on Tuesday which is going to be hell

Hello Everyone,

Hope revision is well

Please could somebody help me in the June 2014 R paper question 5c
https://57a324a1a586c5508d2813730734691051ac35fd.googledrive.com/host/0B1ZiqBksUHNYZ3M4QzJ0N19IeHc/June%202014%20(R)%20QP%20-%20S2%20Edexcel.pdf

How come they poisson to normal approximate rather than binomial to normal approximate because isnt binomial more accurate?

thank you so much!
i just realised i need someone to explain the answer to another question, could you help me again?


2b)

Hey. Can I have some help with this question? (January 2002)


The question says "more than 196 passengers turn up" so its >196. Then, wouldn't it mean that (less than or equal to) 4 do not turn up?

The mark scheme says simply < 4, so I am confused.

So it's not <=7, as 6.9 is closer to 7 than to 6?

You don't know what the probability of a defect occuring is so you can't use binomial. You're told the rate but the mean is 25 so you need to approximate to normal.

Because you're binomial for part (a) should be number who do NOT show up, so it is less than 4

What have I done wrong for part e?

Probability of the tear being longer than 1mm for one customer is o.575

Probability of tear being longer than 1mm for 3 or more customers is binomial with n = 5, p = 0.575
Then P(X>=3) = P(x=3) + P(x=4) + P(x=5)?

I got 0.64

is it because you don't know which side is the shorter side??? so it could be either which is why you add the probabilities for both??