HP 12C manual 104

1.Press CLEAR .

2.Key in the first y-value and press . Key in the first x-value and

press . Repeat this step for each data pair.

3.After all data pairs are input, press to obtain the correlation coefficient (between y and ln x).

4.Press 1 0 to obtain A in the equation above.

5.Press to obtain B.

6.To make a y-estimate, key in the x-value and press .

Example 1: A manufacturer observes declining sales of a soon-to-be obsolete product, of which there were originally 10,000 units in inventory. The cumulative sales figures over a number of months, given below, may be fit by a logarithmic cure of the form y = A + B (ln x), where y represents cumulative sales in units and x the number of months since the beginning. How many units will be sold by the end of eighth months?

Month		1	2		3	4	5	6
Cumulative Sales (units)		1431	3506		5177	6658	7810	8592
Keystrokes		Display
CLEAR
1431	1.00			First pair data input.
1
3506	2.00			Second pair data input.
2
5177	3.00			Third pair data input.
3
6658	4.00			Forth pair data input.
4
7810	5.00			Fifth pair data input.
5
8592	6.00			Sixth pair data input.
6

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