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# Edexcel S2 - 27th June 2016 AM

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1. Is it worth doing exercises from the text book at this point or just exam questions?
2. What's the rules for rounding and accuracy in the answers for S2?
3. Can anyone explain this?

https://57a324a1a586c5508d2813730734...%20Edexcel.pdf

q.1b)

Why is it p(x>=1) in a 2 day interval?

Doesn't the question imply there has to be at least 2 cars in a two day interval?

Zacken SeanFM
4. (Original post by Armpits)
Can anyone explain this?

https://57a324a1a586c5508d2813730734...%20Edexcel.pdf

q.1b)

Why is it p(x>=1) in a 2 day interval?

Doesn't the question imply there has to be at least 2 cars in a two day interval?

Zacken SeanFM
Huh? The question says that in a period of 24 hours, the mean number of cars is 0.8.

So in a period of 48 hours, the mean number of cars is 1.6.

Now, one car has already passed through - you start a countdown as soon as that car passes through. (not counting it) What is the probability that at least one car passes through in the next 48 hours?
5. (Original post by Zacken)
Huh? The question says that in a period of 24 hours, the mean number of cars is 0.8.

So in a period of 48 hours, the mean number of cars is 1.6.

Now, one car has already passed through - you start a countdown as soon as that car passes through. (not counting it) What is the probability that at least one car passes through in the next 48 hours?
Ah right didn't realise it was a countdown. Thanks
6. (Original post by Armpits)
Can anyone explain this?

https://57a324a1a586c5508d2813730734...%20Edexcel.pdf

q.1b)

Why is it p(x>=1) in a 2 day interval?

Doesn't the question imply there has to be at least 2 cars in a two day interval?

Zacken SeanFM
I think the first bit where the car has been caught speeding just defines the start of the time period, just like saying 'it's 12 o'clock now, find the probability that in under 48 hours another car will have been caught speeding'.
7. https://ef8b5216a7366459ac0f2ce0ac13...%20Edexcel.pdf
8. (Original post by AlphaArgonian)
https://ef8b5216a7366459ac0f2ce0ac13...%20Edexcel.pdf
What have you tried?
9. (Original post by AlphaArgonian)
https://ef8b5216a7366459ac0f2ce0ac13...%20Edexcel.pdf
Use ratios to find two probabilities such that one is 1.5 x the other
10. (Original post by SeanFM)
What have you tried?
Hey Sean, any Madmaths questions you've come across that are hard?. I think this paper will be hard cos last year had the highest grade boundaries for the last 7 years...but I can't really think of any topics which can be made really hard
11. (Original post by Nikhilm)
Hey Sean, any Madmaths questions you've come across that are hard?. I think this paper will be hard cos last year had the highest grade boundaries for the last 7 years...but I can't really think of any topics which can be made really hard
I haven't done any I'm afraid - they were made after I sat A-levels, I think. (that, or I hadn't heard of them before) but it's definitely worth flicking through the relevant booklets and looking for questions if you've run out of stuff to do.

That's the thing with stats, they can't throw anything extremely challenging at you. If you're happy with the most recent papers then you should be fine. (Maybe, just maybe, have a look at those kind of distributions with shape questions and make sure you're confident on those (eg uniform distribution models one length of a rectangle, find the area etc).
12. (Original post by SeanFM)
I haven't done any I'm afraid - they were made after I sat A-levels, I think. (that, or I hadn't heard of them before) but it's definitely worth flicking through the relevant booklets and looking for questions if you've run out of stuff to do.

That's the thing with stats, they can't throw anything extremely challenging at you. If you're happy with the most recent papers then you should be fine. (Maybe, just maybe, have a look at those kind of distributions with shape questions and make sure you're confident on those (eg uniform distribution models one length of a rectangle, find the area etc).
Ah okay, thank you!
13. (Original post by SeanFM)
What have you tried?
Not sure where to start tbh
14. (Original post by Nikhilm)
Use ratios to find two probabilities such that one is 1.5 x the other
Um what?
15. (Original post by AlphaArgonian)
Um what?
Notifications aren't working proplerly, sorry (they only show up half the time).

Think about the information given in the question and what you can deduce about the probability of getting a heads/tails.
16. June 15 IAL is a disgusting paper

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17. I don't understand part b. Could someone explain it to me please?
18. (Original post by target21859)
I don't understand part b. Could someone explain it to me please?
Bit tricky, I think as X~B(20,0.2)

20 - X equalling number of failures

S = 4X - (20 - X)
S = 5X - 20

Sent from my iPhone using Tapatalk
19. (Original post by ragreener1)
Bit tricky, I think as X~B(20,0.2)

20 - X equalling number of failures

S = 4X - (20 - X)
S = 5X - 20

Sent from my iPhone using Tapatalk
Where does the 4X come from?
20. (Original post by target21859)
Where does the 4X come from?

Sent from my iPhone using Tapatalk

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