I'm pretty sure I'm right, this also also makes sense time wise and working out wise for 4 marks.
Could you explain whats wrong with the logic of my method or what the actual correct method is?

Reply 44

JayrZ

12

yeah most likely 2/5, maybeeee 3/5 but I wouldn't count on it

Original post by UrBusted

you think we'd get any marks for this bro?? i gurantee at least 50% of people did the same thing

Reply 45

Canary84

15

Original post by JayrZ

yh I did that I did p(x less or = to 13) - p(x less or = to 3) but I got the wrong answer I'm baffed

Think u needed -p(x less or =2)
I looked at it for long time and think that between x and 13 is less than 13 minus all time ur below 3 i.e 0,1,2

Reply 46

asdasd2

2

Original post by JayrZ

yeah most likely 2/5, maybeeee 3/5 but I wouldn't count on it

Mate, that was how you do it. It make the most sense

Reply 47

JayrZ

12

yeah your right

Original post by Canary84

Think u needed -p(x less or =2)
I looked at it for long time and think that between x and 13 is less than 13 minus all time ur below 3 i.e 0,1,2

Reply 48

asdasd2

2

Original post by JayrZ

yeah most likely 2/5, maybeeee 3/5 but I wouldn't count on it

Think about it logically, one step at a time. Forget about e^X and X^2 for a moment, just think about the number of spins it takes to get the colour, if I choose red and it took 3 spins, my score would be e^3. I choose blue and it took 4 spins the score would be 4^2. Thats how their game works.
You need to work out what X (number of spins till you get the colour), is most likely. Thats where you use E(X) to work out the expected number of spins so, so on average it takes 'this' amount of spins to get that colour. And then just work out the score.
I'm 100% positive I'm right.

Reply 49

tbt27

6

I did the same as you but I'm not too sure it is right. The question was 5 marks and this method is definitely not worth 5 marks

Original post by asdasd2

Think about it logically, one step at a time. Forget about e^X and X^2 for a moment, just think about the number of spins it takes to get the colour, if I choose red and it took 3 spins, my score would be e^3. I choose blue and it took 4 spins the score would be 4^2. Thats how their game works.
You need to work out what X (number of spins till you get the colour), is most likely. Thats where you use E(X) to work out the expected number of spins so, so on average it takes 'this' amount of spins to get that colour. And then just work out the score.
I'm 100% positive I'm right.

Reply 50

Statistician384

12

I even did the same thing for the critical region :frown:

Original post by freebirdk

Should get some of the marks but not all... I know a few people did that

Reply 51

hitec25

8

q2 how did one do that?

Reply 52

darie211

For the chi squared one at q4 how did u guys get 3 and 4 degrees of freedom? I got 5 and 4, what was the second constraint?

Reply 53

asdasd2

2

Original post by darie211

For the chi squared one at q4 how did u guys get 3 and 4 degrees of freedom? I got 5 and 4, what was the second constraint?

I got 5 and 4 as well for DOF, but I'm not really sure if its right

Reply 54

Lemur14

Volunteer Section Leader

21

Original post by tbt27

anyone think i would get a pity mark for finding power, not type 2 error or just straight 0/3

I'm thinking a pity two marks, it's only 1-answer so we got most the working right...

Reply 55

darie211

I just don t get where the second constraint is in any of them

Original post by asdasd2

I got 5 and 4 as well for DOF, but I'm not really sure if its right

Reply 56

Moriayo

11

Original post by darie211

I just don t get where the second constraint is in any of them

There was some grouped frequencies and I removed an extra from each because the probabilities were estimates. So first was 5-2 and second was 6-2 I think

Reply 57

tbt27

6

Thanks. I hope so as everyone else seems to have done really well on this test so the grade boundaries are going to be v high.

Original post by Lemur14

I'm thinking a pity two marks, it's only 1-answer so we got most the working right...

Reply 58

tbt27

6

the mean/ probability was estimated in both of them

Original post by darie211

I just don t get where the second constraint is in any of them

Reply 59

freebirdk

OP

8

6 columns to begin with
Combining columns 5 and 6 so that E>5 makes 5 columns.
-1 because the total is constrained to 80 makes 4 DOF.
-1 because p has been estimated from the data makes 3 DOF.

In the poisson one, it's 4 DOF because you don't need to combine columns 5 and 6.

Original post by darie211

For the chi squared one at q4 how did u guys get 3 and 4 degrees of freedom? I got 5 and 4, what was the second constraint?

(edited 4 years ago)

Edexcel Further Statistics 1 - UNOFFICIAL MARK SCHEME [18 June 2019]

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