HP 39g Graphing Calculator - Manual (Page 115)

Calculating predicted values
Find predicted
values
H I N T
The functions PREDX and PREDY estimate (predict) values
for X or 7 given a hypothetical value for the other. The
estimation is made based on the curve that has been calculated
to fit the data according to the specified fit.
1. In Plot view, draw the regression curve for the data set.
2. Press 0 to move to the regression curve.
3. Press isSSiS and enter the value of X. The cursor jumps to
the desired point on curve and the coordinate display
shows X and the predicted value of Y.
In HOME,
- Enter PREDX(y-va/M(?) | enter ]
to find the predicted (estimated) value for the
independent variable given a hypothetical dependent
value.
- Enter PREDY(x-value) to find the predicted value of
the dependent variable given a hypothetical
independent variable.
You can type PREDX and PREDY into the edit line, or
you can copy these function names from the MATH
menu under the Stat-Two category.
In cases where more than one fit curve is displayed, the
PREDY function uses the most recently calculated curve. In
order to avoid errors with this function, uncheck all fits except
the one that you want to work with, or use the Plot View
method.
Statistics aplet 8-21