HP 12C Financial 0012C-90001, 12C Financial 12C#ABA, 12C Financial F2231AA#ABA Weighted Mean, 0gR, 1 gR~d, Display, Display, Example:, Example:, Keystrokes, Keystrokes

Section 6: Statistics Functions 81

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
	0.001	= 0.
1 gR~d~-		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.

File name: hp 12c_user's guide_English_HDPMBF12E44	Page: 81 of 209
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