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Edexcel S1 - 15th June, 2016 [Exam Discussion]

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Original post by Themathgeek
I have a question about the Sarah and Rebecca winnings one.

Basically how do you do it

Do they each spin individually or is it 1 spin only tat determine both of their scores if that makes sense?

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One spin determines both of their scores. So basically, you have to work out the probability that 1/X > X and 1/X < X to work out who would win. There were five possible values for X; in two of them (3/2 and 2), Sarah won and in another two (-2 and 1/2), Rebecca won (the fifth option of -1 would have been a draw); sum the probabilities associated with those outcomes together (sorry but I can't remember the probability distribution) to get the answers of 0.475 and 0.375, respectively.

Original post by NickDacre
did anyone get 0.81 and 0.405 for the P(DIBnD) and P(BnD':wink:??
I'm afraid I got 0.45 and 0.405, and I'm pretty sure both were correct.
how do you get E(R) to be 0.45?

is it correct to form a table for R with 1/X values and keep the probabilities the same?
Original post by ShatnersBassoon
One spin determines both of their scores. So basically, you have to work out the probability that 1/X > X and 1/X < X to work out who would win. There were five possible values for X; in two of them (3/2 and 2), Sarah won and in another two (-2 and 1/2), Rebecca won (the fifth option of -1 would have been a draw); sum the probabilities associated with those outcomes together (sorry but I can't remember the probability distribution) to get the answers of 0.475 and 0.375, respectively.

I'm afraid I got 0.45 and 0.405, and I'm pretty sure both were correct.


Yes, exactly :smile:
Original post by olyatrunova
For the number of diners, did anyone get 16 or 17?


I got that! But i think i crossed it off and put 25. I can't remember :smile:


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I thought tet test was alright - a lot easier than C1 and C2. I dropped marks in the the venn diagram section because I only understood what to do in the question about B and D being independent in like the last 5 minutes
Original post by imran_
id say i got around 69-70 for C1
67-68 for c2
52+ for s1

my overall grade?


Might be in luck for an A! But defo a B :smile:


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Original post by iMacJack
How to get 33 customers model answer!

P(D|RnB) = 0.45 and P(D|RnB':wink: = 15/37

It says that 40 customers have rented a room and eaten breakfast
It also says that 37 have rented a room and not had breakfast

Well, we worked out the chance of them having dinner given those conditions in the two previous parts, so all we needed to do was 40*0.45 + 37 * 15/37 to come to our answer of 18+15 = 33 customers.

Hope this clears it up


Read this. Anyone who needs clarification
I got 5/6 in the question 4 d ii ?????? Can anyone explain where I went wrong???? I did 0.15/0.18


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will there be model solutions for this?
Original post by bobbutitii
Urm i think it is cocky you ****


Like I give a ****. Go revise u pussy.
Original post by imran_
id say i got around 69-70 for C1
67-68 for c2
52+ for s1

my overall grade?


Low/Mid A
For C1 I got 47/75 C2 I got 62/75 and for S1 I got 68/75. What overall grade would this be? I was thinking a high B maybe... If I resat C1 would I have a chance of raising my grade to an A?
Original post by ShatnersBassoon
One spin determines both of their scores. So basically, you have to work out the probability that 1/X > X and 1/X < X to work out who would win. There were five possible values for X; in two of them (3/2 and 2), Sarah won and in another two (-2 and 1/2), Rebecca won (the fifth option of -1 would have been a draw); sum the probabilities associated with those outcomes together (sorry but I can't remember the probability distribution) to get the answers of 0.475 and 0.375, respectively.

I'm afraid I got 0.45 and 0.405, and I'm pretty sure both were correct.


Oh ffs so i read the question for that wrong

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Original post by hogree
That was it matey.



That the way I did it. Almost certain that was right.

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I did exactly this. I drew a table and all and found that three draws were possible.

I got 0.4 something and 0.4 something.
I got some weird different values for p and q 😭- will I st least get some method marks ?? If I calculated everything correctly using those values ?
Can someone explain how to dothe P(D/RnB) one? Thanks


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Original post by 15anonymous
I got some weird different values for p and q 😭- will I st least get some method marks ?? If I calculated everything correctly using those values ?


As long as you had the correct method i.e. adding it all up and making it equal to 1 etc to find P and Q you will get method marks.

As for the other questions that relied on the values of P and Q, you should get e.c.f. (error carry forward) marks.
can anyone clarify how to calculate E(R)?
Reply 1438
Can someone explain how to calculate Syy with sd and mean please?
are we allowed to post the question paper on here?

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