HP 12C Financial calculator - Manual (Page 81)

Section 6: Statistics Functions 81
File name: hp 12c_user's guide_English_HDPMBF12E44 Page: 81 of 209
Printered Date: 2005/7/29 Dimension: 14.8 cm x 21 cm
Example: Compute the slope and intercept of the regression line in the preceding
example.
Keystrokes Display
0gR 15.55 y-intercept (A); projected value for x
= 0.
1 gR~d~- 0.001 Slope of the line (B); indicates the
change in the projected values
caused by an incremental change in
the x value.
The equation that describes the regression line is:
y = 15.55 + 0.001x
Weighted Mean
You can compute the weighted mean of a set of numbers if you know the
corresponding weights of the items in question.
1. Press fCLEAR².
2. Key in the value of the item and press \, then key in its weight and press
_. Key in the second item’s value, press \, key in the second weight,
and press _. Continue until you have entered all the values of the items and
their corresponding weights. The rule for entering the data is “item \
weight _.”
3. Press g to calculate the weighted mean of the items.
Example: Suppose that you stop during a vacation drive to purchase gasoline at
four stations as follows: 15 gallons at $1.16 per gallon, 7 gallons at $1.24 per
gallon, 10 gallons at $1.20 per gallon, and 17 gallons at $1.18 per gallon. You
want to find the average cost per gallon of gasoline purchased. If you purchased
the same quantity at each station, you could determine the simple arithmetic
average or mean using the Ö key. But since you know the value of the item
(gasoline) and its corresponding weight (number of gallons purchased), use the 
key to find the weighted mean:
Keystrokes Display
fCLEAR² 0.00 Clears statistics registers.
1.16\15_ 1.00 First item and weight.
1.24\7_ 2.00 Second item and weight.
1.20\10_ 3.00 Third item and weight.
1.18\17_ 4.00 Fourth item and weight.