HP 12c Solutions Handbook page 105

1. Press
2. Key in the first y-value and press
press
3. After all data pairs are input, press
coefficient (between y and ln x).
4. Press 1
5. Press
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
cumulative sales in units and
How many units will be sold by the end of eighth months?
Month
Cumulative Sales (units)
Keystrokes
CLEAR
1431
1
3506
2
5177
3
6658
4
7810
5
8592
6
CLEAR .
. Repeat this step for each data pair.
0
to obtain B.
the number of months since the beginning.
x
1431
Display
1.00
2.00
3.00
4.00
5.00
6.00
. Key in the first x-value and
to obtain A in the equation above.
= + (ln
y A B
1 2 3
3506 5177
First pair data input.
Second pair data input.
Third pair data input.
Forth pair data input.
Fifth pair data input.
Sixth pair data input.
104
to obtain the correlation
), where represents
x y
4 5
6658 7810 8592
.
6