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Edexcel S3 - Wednesday 25th May AM 2016 watch

1. Did anyone else use the poisson formula to find the mean? I.e. e^-lambda = 16.53/100, and solve for lambda? I got the mean to be 1.7999... which gave me the same expected values and overall test statistic.
2. (Original post by Unravelling)
Did anyone else use the poisson formula to find the mean? I.e. e^-lambda = 16.53/100, and solve for lambda? I got the mean to be 17.999... which gave me the same expected values and overall test statistic.
Wasn't lamda 1.8?
3. (Original post by Rkai01)
Wasn't lamda 1.8?
Sorry! I meant 1.799...
4. For the binomio question hypothesis can you write ' a binomial distribution with p=0.3 is a suitable model for the data' ?
5. (Original post by Unravelling)
Sorry! I meant 1.799...
Not 1.799, 1.8 dude
6. (Original post by Unravelling)
Sorry! I meant 1.799...
Yeh i got that
7. (Original post by Rkai01)
Not 1.799, 1.8 dude
But what's wrong with doing it my way? I calculated the value of the mean using the manual poisson method
8. (Original post by Unravelling)
But what's wrong with doing it my way? I calculated the value of the mean using the manual poisson method
I don't know what that is dude everyone is saying 1.8 so maybe it's fine depending on which way you chose but in the book it shows sum of x times f(x) divided by n
9. (Original post by Rkai01)
I don't know what that is dude everyone is saying 1.8 so maybe it's fine depending on which way you chose but in the book it shows sum of x times f(x) divided by n
Using the S2 formula for poisson, (e^-λx λ^n)/(n!), for when x = 0 the expected value is 16.53 so the probability is 0.1653, and then n = 0 so e^-λ= 0.1653 and then λ gave me 1.799... which added up with all the other expected frequencies given and my answers were the same as those who used λ = 1.8
10. (Original post by Unravelling)
Using the S2 formula for poisson, (e^-λx λ^n)/(n!), for when x = 0 the expected value is 16.53 so the probability is 0.1653, and then n = 0 so e^-λ= 0.1653 and then λ gave me 1.799... which added up with all the other expected frequencies given and my answers were the same as those who used λ = 1.8
Yeh i did tht

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11. (Original post by physicsmaths)
Yeh i did tht

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good to see that it wasnt just me then
12. (Original post by Unravelling)
Using the S2 formula for poisson, (e^-λx λ^n)/(n!), for when x = 0 the expected value is 16.53 so the probability is 0.1653, and then n = 0 so e^-λ= 0.1653 and then λ gave me 1.799... which added up with all the other expected frequencies given and my answers were the same as those who used λ = 1.8
Oh S2 I remember that been awhile since AS days I forget everything after 1 week lol
13. (Original post by JoshC98)
For the binomial question, did anybody else round 0.405 to 0.40 rather than 0.41? Because 0.41 would have made the total expected frequency 50.01 rather than 50?
bump
14. (Original post by Rkai01)
Oh S2 I remember that been awhile since AS days I forget everything after 1 week lol
yeah I can imagine, I'm doing all of further maths this year though so I've yet to actually do the S2 exam :P
15. (Original post by Unravelling)
yeah I can imagine, I'm doing all of further maths this year though so I've yet to actually do the S2 exam :P
Damn what are your other mods?
16. (Original post by Unravelling)
good to see that it wasnt just me then
How else did people do it? Guess that was why i thought that questions was really tricky and that the method was hard to spot.

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17. (Original post by JoshC98)
For the binomial question, did anybody else round 0.405 to 0.40 rather than 0.41? Because 0.41 would have made the total expected frequency 50.01 rather than 50?
I got something similar, I initially rounded both the first and last expected values up but was 0.1 over, so just rounded the last one (can't remember if that was 0.405) down.
18. (Original post by physicsmaths)
How else did people do it? Guess that was why i thought that questions was really tricky and that the method was hard to spot.

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I had no idea of any other way to do it :P When i asked other classmates, none of them did it our way and just calculated it from the tables (0 x its probability, 1 x its probability etc). which I didn't get since there were missing values we had to solve
19. (Original post by ChrisP97)
I got something similar, I initially rounded both the first and last expected values up but was 0.1 over, so just rounded the last one (can't remember if that was 0.405) down.
I think it was 12.005 for the first one, and 0.405 for the last one, so if you rounded to 12.01 and 0.41 you ended up being 0.01 over, so last one had to be adjusted to 0.40.

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