Need Help With A A Level Statistics Question

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Eager PPe ist
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#1
Report Thread starter 12 years ago
#1
Hey folks,

if any mathematicians doing Statistics 2 unit for edexcel could help me out that would be great since i ve found this problem that's driving me mental

to find it look in Statistics 2 (Heineman book) page 35 question 4 part d
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- skyhigh -
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#2
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#2
Maybe you can scan the question and attach it?
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sweetfloss
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#3
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#3
Yeah, I loved S2 when I did that module, but I sold my textbook on to someone in the year below before I came to uni so I can't help unless I see the question!
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Eager PPe ist
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#4
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#4
ok cheers guyz here's the question :

A bakery claims that a pack of 10 of their teacakes contains on average 75 currants.

a) Suggest a distribution thqt could be used to model the number of currants in a randomly selected teacake. State any assumptions that must be made for the model to be valid.

b) Specify the value of any parameters

c)Show that the probability that a randomly selected teacake contains more than 7 currants is 0.475

d)Calculate the probability that in a pack of 10 teacakes at least 2 teacakes contain more than 7 currants. ( this was the one i couldn't do!)

the answer for part d in the book says 0.984 how on earth do you get that!
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Eager PPe ist
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#5
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#5
By the way this is a poisson / Binomial distribution type of question
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Simba
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#6
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#6
Well, you have a distribution: X ~ B(10, 0.475). You want to find P(X >= 2).

Can you do it from here ?
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Eager PPe ist
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#7
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#7
can i not use poisson?
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Simba
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#8
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#8
Not for part 'd' you can't since there is a fixed number of trials (10 teacakes in the pack).
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James
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#9
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(Original post by Eager PPe ist)
can i not use poisson?
Not really. We're modelling the number of successes in n independent trials, each with known probability of success p, which is B(n,p).
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Eager PPe ist
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#10
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#10
but when i do 1-(probabilities of 0+1+2) from the binomial formula i get 1-(0.0016+0.0144+0.0586) = 0.9254 which is wrong
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Eager PPe ist
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#11
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#11
YEES cheers guyz i got it , it was p(x greater or equal to 2)
thank you so much
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James
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#12
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#12
Well done.
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Mashes
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#13
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#13
How do you do part c?
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RDKGames
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#14
Report 2 years ago
#14
(Original post by Mashes)
How do you do part c?
This thread is old and the question is nowhere to be found by the looks of it. If you need help with this question, please start a new thread and attach the imagine of the question along with your attempt(s)
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