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# IB Stats Question Help Watch

1. I've attached the question and my current working out thus-far. I'm stuck with part D.
2. (Original post by BananaPie)

I've attached the question and my current working out thus-far. I'm stuck with part D.
Find the value for the critical region of the 5% significance level for the probability density function and compare that to .

If then you accept the null hypothesis
3. I understand that my degree of freedom of 1, so does that mean that

(2/9)(x-45)^2 < x^2pdf(0.05,1)
?
4. (Original post by BananaPie)
I understand that my degree of freedom of 1, so does that mean that

(2/9)(x-45)^2 < x^2pdf(0.05,1)
?
If x^2pdf(0.05, 1) represents the critical value at the 5% significance level for 1 degree of freedom, then yes
5. (Original post by Felix Felicis)
If x^2pdf(0.05, 1) represents the critical value at the 5% significance level for 1 degree of freedom, then yes
as x^2(0.05,1) = 1.74 (3sf)

Doing that I get 42.2<x<47.8 which turns into x = 43,44,45,46,47

However the answer includes 41,42,48,49 as well. I'm missing something =S
6. (Original post by BananaPie)
as x^2(0.05,1) = 1.74 (3sf)

Doing that I get 42.2<x<47.8 which turns into x = 43,44,45,46,47

However the answer includes 41,42,48,49 as well. I'm missing something =S
I got which made my range of x values thus x = 41, 42, 43, 44, 45, 46, 47, 48, 49
7. (Original post by Felix Felicis)
I got which made my range of x values thus x = 41, 42, 43, 44, 45, 46, 47, 48, 49
Where did you get 3.841 from? =[

Edit: It's written in the data booklet /facepalm. But surely there's a way to calculate it via GDC?
8. (Original post by BananaPie)
Where did you get 3.841 from? =[

I used a different statistics table which gave it to 3 decimal places but 3.84/ 3.841 same thing :P
9. (Original post by BananaPie)
Where did you get 3.841 from? =[

Edit: It's written in the data booklet /facepalm. But surely there's a way to calculate it via GDC?
I usually use the stats table to work out the critical values and don't have a GDC, sorry :P
10. (Original post by Felix Felicis)

I used a different statistics table which gave it to 3 decimal places but 3.84/ 3.841 same thing :P
Yeah, the data booklet we have for our exam includes all the critical values for x^2 distribution. I was pretty sure there was a way to calculate it via GDC though so I was occupied on finding out how. =S

Thanks for the help! ^^
11. (Original post by BananaPie)
Yeah, the data booklet we have for our exam includes all the critical values for x^2 distribution. I was pretty sure there was a way to calculate it via GDC though so I was occupied on finding out how. =S

Thanks for the help! ^^
GDCs are for wimps bro

No problem! Best of luck with your IB exams! I do A-levels but go to a school which does IB as well
12. (Original post by Felix Felicis)
GDCs are for wimps bro

No problem! Best of luck with your IB exams! I do A-levels but go to a school which does IB as well
Wimps!? XD They reduce the time taken to solve questions on my stat paper by like 70%-80%.

And thanks =]. Good luck on ur A-Level exams if you're taking them this year as well!
13. (Original post by BananaPie)
Wimps!? XD They reduce the time taken to solve questions on my stat paper by like 70%-80%.

And thanks =]. Good luck on ur A-Level exams if you're taking them this year as well!
I just had an idea...does your graphics calculator have an equation solver?
14. (Original post by Felix Felicis)
I just had an idea...does your graphics calculator have an equation solver?
Equation Solver? It may have one, but I probably don't know it's called an "Equation Solver". I use a Ti84 Plus.
15. (Original post by BananaPie)
Equation Solver? It may have one, but I probably don't know it's called an "Equation Solver". I use a Ti84 Plus.
It should do...

But I was thinking, if you let denote the probability density function for the function.

Then by definition

If your graphics calculator had an equation solver, then you could solve for and you should get the critical value Alternatively, use the data booklet
16. (Original post by Felix Felicis)
It should do...

But I was thinking, if you let denote the probability density function for the function.

Then by definition

If your graphics calculator had an equation solver, then you could solve for and you should get the critical value Alternatively, use the data booklet
Perhaps it does, I'll have to ask my teacher if such a thing exists on our version of the GDC. I've never heard of it done that way before so it's surprising, but I'll have to check and see.

The thing about the data booklet is that I keep forgetting we have a table of values. It's a habit of mine to believe that everything can be given to u on a GDC if it's a calc paper, unless the question itself is algebraic.
17. (Original post by BananaPie)
Perhaps it does, I'll have to ask my teacher if such a thing exists on our version of the GDC. I've never heard of it done that way before so it's surprising, but I'll have to check and see.

The thing about the data booklet is that I keep forgetting we have a table of values. It's a habit of mine to believe that everything can be given to u on a GDC if it's a calc paper, unless the question itself is algebraic.
I found this which might be of interest :]

http://www.dummies.com/how-to/conten...on-solver.html

Edit: Not saying you're a dummy! :P
18. (Original post by Felix Felicis)
I found this which might be of interest :]

http://www.dummies.com/how-to/conten...on-solver.html

Edit: Not saying you're a dummy! :P
Wait. Is Equation Solver an "Application"? Or is it a program that is hidden somewhere? Because if it's an application then the only ones I'm allowed are 1)Finance, 2) CtlgHelp and 3) PlySmlt2
19. (Original post by BananaPie)
Wait. Is Equation Solver an "Application"? Or is it a program that is hidden somewhere? Because if it's an application then the only ones I'm allowed are 1)Finance, 2) CtlgHelp and 3) PlySmlt2
No idea

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