HP HP12C hp 12c_user's guide_English_E_HDPMBF12E44.pdf - Page 81

Section 6: Statistics Functions 81 Example: Compute the slope and intercept of the regression line in the preceding example. Keystrokes 0gR 1 gR~d~- Display 15.55 0.001 y-intercept (A); projected value for x = 0. 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 fCLEAR² 1.16\15_ 1.24\7_ 1.20\10_ 1.18\17_ Display 0.00 1.00 2.00 3.00 4.00 Clears statistics registers. First item and weight. Second item and weight. Third item and weight. Fourth item and weight. File name: hp 12c_user's guide_English_HDPMBF12E44 Printered Date: 2005/7/29 Page: 81 of 209 Dimension: 14.8 cm x 21 cm