I don't have a TI-84 with me and need to get the equation for the following data:
x-5 10 15 20
y- 7.8 27.8 31.6 33.9
lnreg ^
+33661 A logistic curve (function f(x) below) seems to fit reasonably well.
However, there is no such thing as the equation, in general, when creating curves that are a best-fit to a few data points. You can fit lots of curves to this data; some will fit better than others. Did you have a particular type of curve in mind? Your title suggests you want a logarithmic fit of some sort, but straight line fits to ln(y) vs x; y vs ln(x) or ln(y) vs ln(x) all give very poor fits!
+33661 A logistic curve (function f(x) below) seems to fit reasonably well.
However, there is no such thing as the equation, in general, when creating curves that are a best-fit to a few data points. You can fit lots of curves to this data; some will fit better than others. Did you have a particular type of curve in mind? Your title suggests you want a logarithmic fit of some sort, but straight line fits to ln(y) vs x; y vs ln(x) or ln(y) vs ln(x) all give very poor fits!
