**quick Help Please** (1 Viewer)

[heath]

i need to find the correlation between these two variables X and Y. given


_____X____Y__|
a_|__1__|__3__|
b_|__2__|__3__|
c_|__4__|__6__|
d_|__5__|__8__|

 

[jm1234567890]

is that the question???

what kind of correlations

as in y = something(x) ???

 

[...]

is this like finding the relation between x and y??

 

[sukiyaki]

did you put the points and plot teh graph???

 

[Fosweb]

There are so many possibilities for what this relationship could be...

Example: Using Excel, plotting points, adding a polynomial trend line to 3rd degree, and showing the equation gives this:
y = -0.0833x^3 + 1.0833x^2 - 2.6667x + 4.6667

Not that that will help you in any way really...

 

[iambored]

Originally posted by sukiyaki
did you put the points and plot teh graph???

yeah plot the points and then figure out the equation of the graph

 

[...]

but what happens if the graph is a curve not a straight line?

 

[iambored]

Originally posted by ...
but what happens if the graph is a curve not a straight line?

u figure out the equation of the curve
does this really belong in the ext1 forum?? because, if it's a curve, like a parabola, if you do ext1 then u will know how to find the equation

if u just wanted help from ext1 students then that's cool

 

[...]

wtf...

i never got taught how to find an equation for a curve!!! unless i know where it cuts the axis...

 

[Fosweb]

Originally posted by iambored
u figure out the equation of the curve

I posted the equation in the above post. Did you get any other equations?
I can't get it to work on anything less than a degree 3 polynomial.

 

[iambored]

Originally posted by Fosweb
I posted the equation in the above post. Did you get any other equations?
I can't get it to work on anything less than a degree 3 polynomial.

oh.. ok thats a weird curve... i don't know

Originally posted by ...
wtf...

i never got taught how to find an equation for a curve!!! unless i know where it cuts the axis...

as in parabola u would have, but i didn't realise how complicated that curve was

 

[...]

Originally posted by iambored
as in parabola u would have, but i didn't realise how complicated that curve was

u serious!?!?!?

i better read through all maths books i have now...eek!

 

[iambored]

wait...

let me think, i'm sure i know how to find the equation of a parabola... eek!! from me...


edit: surely i learnt that, i'm sure...

anyway, now the only way i can think of it is from intercepts, like intercepts of 4 and 5 mean (x-4)(x-5) hmmm.. i'm so confused

 

[...]

Originally posted by iambored
wait...

let me think, i'm sure i know how to find the equation of a parabola... eek!! from me...

i think i know how to work if out if the curves were given where it cuts the axis...

but from just looking at it without given the info(ie. the roots) how can u work it out?!?!?!

 

[underthesun]

Never seen these kind of question for 3unit before..

 

[heath]

i tried to work out equation of curve using general form of parabola then working out what a,b,c equal by subbing in the points written above.

but i can't get a parabola to work, so maybe its a cubic?
but i can't work out the equation of a cubic using 4 points and general form can u?

 

[Huy]

Why is this in two forums? I just thought it was weird...perhaps heath is trying to get double the responses in half the time?

It's either 2U or 3U, but not both? (I tend to think that it is more of an Extension 1 question than a 2U Maths Q).

 

[Fosweb]

I tend to think it is neither, and is more something that would get asked at a 'Math Day' or the like...
Maybe its not a graph, but a series/pattern etc...

 

[heath]

no its all kool

it was a cubic.

y = (-1/12)x3 + (13/12)x2 - (8/3)x + (14/3)

thanks guys.


p.s no parabola works

 

[Fosweb]

Congratulations Excel. Thats a cool feature. I dont think this type of question will come up unless you are given more information. Where did this qu come from?