power function/exponential function help

[nels]

this is a question from vcaa 02 exam 1.

x      y
1     1.6
2     2.6
3     4.3
4     7.0
5     11.3
6     18.4
7     29.9
8     48.5

the data would be best modelled using
A. a linear function
B. a power function
C. an exponential function
D. a circular function
E. a logarithmic function

i know that it is either B or C. how can i now determine which is correct? what factor separates the two?
thanks.

[GoodGuys]

C,
as x increase, so does y. Thus, the best option will be C

[TrueTears]

The best way is to type this in the TI-89, put x in list 1 and y in list 2 and then use regressions.

[bem9]

this is a question from vcaa 02 exam 1.

x      y
1     1.6
2     2.6
3     4.3
4     7.0
5     11.3
6     18.4
7     29.9
8     48.5

the data would be best modelled using
A. a linear function
B. a power function
C. an exponential function
D. a circular function
E. a logarithmic function

i know that it is either B or C. how can i now determine which is correct? what factor separates the two?
thanks.

Power function is x^n, where n is a fraction or integer like 2/3, -1, 2 etc... i think
but exponential is in the form a^x, where a is a constant.
So its C

[nels]

thanks guys.

The best way is to type this in the TI-89, put x in list 1 and y in list 2 and then use regressions.

if i used this method, how will i know which is the correct answer?

[TrueTears]

thanks guys.

The best way is to type this in the TI-89, put x in list 1 and y in list 2 and then use regressions.

if i used this method, how will i know which is the correct answer?

Well first of all you had a hunch that it's either B or C, so go into stats list editor type your stuff in and then pick F4 9, for powerreg, if the coefficient of correlation is not close to 1 then pick F4 8 which is exponential reg, this will give a coefficient of correlation very close to 1, thus it must be C.

[naved_s9994]

Tt
wouldn't it take longer by doing that?
(statlist editor)

[TrueTears]

Tt
wouldn't it take longer by doing that?
(statlist editor)

no, very fast if you know your stuff.

[NE2000]

thanks guys.

The best way is to type this in the TI-89, put x in list 1 and y in list 2 and then use regressions.

if i used this method, how will i know which is the correct answer?

Well first of all you had a hunch that it's either B or C, so go into stats list editor type your stuff in and then pick F4 9, for powerreg, if the coefficient of correlation is not close to 1 then pick F4 8 which is exponential reg, this will give a coefficient of correlation very close to 1, thus it must be C.

Yeah that's what I do. Won't ever fail you unless you type it in wrong. In the TI-84 you have to make sure you have DiagnosticOn to see R^2 values. The R^2 values are basically how well the correlation exists.

[nels]

ahh i see. didnt have the diagnostic on before so that was why i was wondering...
thanks guys, heaps of help as usual!