HP 12c Platinum Reference Manual page 86

86 Forecasting
3. Key in the first point of group I and press \(³)
4. Key in the first point of group II and press \(³).
5. Key in the first point of group III and press t.
6. Repeat steps 3, 4, and 5 for the balance of the data in each group. After executing step
5 the display shows how many sets of data have been entered.
7. To fit the data to a Gompertz curve, press g(013t . The resultant display is
the curve constant "a". Constants "b" and "c" may be obtained by pressing :6 and
:7 respectively. The display may need adjusting to see significant digits.
8. To calculate a projected value, key in the number of the period and press t.
9. Repeat step 8 for each period desired.
Example: The X-presso Company marked a revolutionary new coffee brewing machine
in 1990. Sales grew at a steady pace for several years, then began to slow. The sales
records for the first 9 years of the product's life were as follows.
What are the projected sales volumes for this product in its 10th and 12th year? What is
the maximum yearly sales volume for this product if the present trend continues? What
annual sales rate would the curve have predicted for the 5th year of the product's life?
(Arrange the data as follows:)
12c platinum / 12C
RPN Keystrokes
fCLEARH
18\
151\
282t
41\
188\
322t
49\
260\
340t
Year Sales($K)
1 18
2 41
3 49
4 151
5 188
Group I Group II
18
41
49
12c platinum
ALG Keystrokes
fCLEARH
18³
151³
282t
41³
188³
322t
49³
260³
340t
Year Sales($K)
6 260
7 282
8 322
9 340
Group III
151 282
188 322
260 340
Display
0.00
18.00
151.00
1.00
41.00
188.00
2.00
49.00
260.00
Total number of entries.
3.00
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