# Arsey's S1 Edexcel Answers 18th Jan 2013Watch

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#261
Would I get a mark for writing 'a discrete random variable' for when they ask 'State the name of this probability distribution.'?
No

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#262
(Original post by Chris-69)
Hi Arsey,

Quick question with regards to 4c:

I did P(L>133 | L>127) = P(127< L < 133) / P(L>127)

And then inserted the values. How many marks would this gain me? 1?

Thanks!
Yes 1

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#263
(Original post by pilotluke1)
Also for 3d i said 'this is reliable because 10 degrees is inside the data range of 8-30 degrees' would i get the mark?
Yep that is what is in the proper MS, sort of.

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#264
(Original post by pilotluke1)
For question 6f I multiplied 0.5 by each probability of her winning and added it all together and got seven twelths! I also said which die to pick but not the probability of winning for each die! how many marks?
If you very clearly stated which dice to choose for each number the coin lands on you get 2, which is rather generous I thought.

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#265
(Original post by Vorsah)
Say if in a question I get part A wrong which is worth 2 marks

Then in part B I use the answer I get in part A to get answer, which is worth 2 marks.

Will I only lose 2 marks for part A, so I would get 2/4 in total?
Depends on the MS normally you would just get the next method but not the final accuracy.

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#266
(Original post by Yohann)
Hi Arsey....Thnks for the Marking scheme!
I had a question regarding the Venn diagram!
When drawing the Venn diagram, I wrote 0.32 in the B cirlce instead of 0.23 which also affected the P(AUBUC)^l to be wrong...so out of four how many marks will i lose? one or two?
From wht i think, i could be one as 1 mark would be for drawing the diagram correctly, 1 mark for the cirlce of A, 1 mark for the circle of B and the last mark for the circle of B and outside!

Pls give ur opinion! thnks
You will get 2/4

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#267
(Original post by gooner4ever)
Quick question guys do you think I'll lose marks for the probability distribution for B (question 6a) if I wrote the x values of 1 and 3 and 5 separately e.g X 1 1 3 3 5 5 and then the probability of each 1/6 as opposed to what's done in the model answers (joining them all together) ???
cos they way I did it isn't wrong just not well done!
That is wrong so you will get no marks

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6 years ago
#268
(Original post by Arsey)
You will get 2/4

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Hi arsey

For the dice question I got 5/12 but I didn't draw a tree diagram at all, but I more or less wrote everything else that is on your mark scheme. Will I gt all 4 marks, or only 2?

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#269
(Original post by wtrmln1245)
How many Marks do you believe i can get for just calculating p>133 correctly? I missed out the whole given that thank you so much for the help
This one has probably been answered 10 times now.

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#270
(Original post by Chris-69)
Paper Q4C: http://papers.xtremepapers.com/Edexc...olomon%20K.pdf
Mark scheme Q4C: http://papers.xtremepapers.com/Edexc...n%20K%20MS.pdf

Why is the working out for this question not the same as the one in the Jan 2013 paper?
Very similar question.

Would be the same if the question said. What is the prob the phone ran out during the journey. We had to work out that it lasted the journey.

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#271
(Original post by totw)
Hi arsey

For the dice question I got 5/12 but I didn't draw a tree diagram at all, but I more or less wrote everything else that is on your mark scheme. Will I gt all 4 marks, or only 2?

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You didn't need the tree. I wouldn't have bothered. However the MS is very clear you must clearly show which dice to use for each value the coin lands on. So as long as that was obvious 4/4

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6 years ago
#272
(Original post by Arsey)
You didn't need the tree. I wouldn't have bothered. However the MS is very clear you must clearly show which dice to use for each value the coin lands on. So as long as that was obvious 4/4

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I also didn't use a tree diagram, but I also thought the coin probability was superfluous because she could win either way, thus I thought Arisha winning or not was entirely dependant on choosing the correct dice, which they assumed you would figure. So my calculation basically was the probability of her winning (excluding the coin probability of * by 0.5) divided by all the possibilities ( her winning and losing) but because I excluded coin probability, I wasn't dividing by one, and I got 5/12 for my answer - surely that can't be a coincidence?
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6 years ago
#273
Hi everyone,
If take look at S1 June 2010 paper, it more straightforward than this and the grade boundaries were 55 for an A
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6 years ago
#274
(Original post by Arsey)
That is wrong so you will get no marks

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Not even 1/2?

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6 years ago
#275
(Original post by Arsey)
Very similar question.

Would be the same if the question said. What is the prob the phone ran out during the journey. We had to work out that it lasted the journey.

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Ah, god dammnit. I think it was pretty out of order to give such an awkward question which carried 4 marks.
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6 years ago
#276
6F) is horrifically worded - why didn't they say find the probability that avisha wins when she picks the best die rather than just saying the probability that she wins making it ambiguous.

I know they said she picks the best one before, but the question just says the probability that she wins
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6 years ago
#277
(Original post by JASONDILL)
6F) is horrifically worded - why didn't they say find the probability that avisha wins when she picks the best die rather than just saying the probability that she wins making it ambiguous.

I know they said she picks the best one before, but the question just says the probability that she wins
The question clearly states 'Avisha chooses the die which gives her the best chance of winning each time Tom spins the coin'.

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6 years ago
#278
(Original post by geor)
Yes, true, but it doesn't clearly state that THAT is the probability you should be calculating. It says calculate the probably that she wins. Unclear.

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What did her winning mean to you, then?
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6 years ago
#279
What did her winning mean to you, then?
The important bit is that she 'chooses the die', meaning that she chooses one die...

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6 years ago
#280
(Original post by ljh950912)
The important bit is that she 'chooses the die', meaning that she chooses one die...

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Yeh ik, I got this question right - I don't understand everyone's problem with the wording.. There only dumb question in the entire paper was that damn distribution question on the phone that transforms after 127 hours.
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