HP 113394 User Guide - Page 99

Section 6: Statistics Functions 99 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 gÖ keys. But since you know the value of the item (gasoline) and its corresponding weight (number of gallons purchased), use the g keys to find the weighted mean: Keystrokes Display fCLEAR² 1.16\15_ 1.24\7_ 1.2\10_ 1.18\17_ g 0.00 1.00 2.00 3.00 4.00 1.19 Clears statistics registers. First item and weight. Second item and weight. Third item and weight. Fourth item and weight. Weighted mean cost per gallon. A procedure for calculating the standard deviation and standard error (as well as the mean) of weighted or grouped data is included in the hp 12c platinum Solutions Handbook. File name: hp 12c pt_user's guide_English_HDPMF123E27 Page: 99 of 275 Printed Date: 2005/8/1 Dimension: 14.8 cm x 21 cm