Information Technology Reference
In-Depth Information
x
10
9
6.5
6
5.5
5
4.5
4
3.5
3
2.5
1950
1955
1960
1965
1970
1975
1980
1985
1990
1995
2000
Fig. 5.13
The figure shows the graph of an exponential population model p
D
p.t/ together with
the actual measurements marked by the open marks
In Fig.
5.13
, we have plotted the estimated population p.t/,givenby(
5.83
),
together with the actual population from 1955 to 2000. Again we note that the model
gives extremely good predictions.
What about the future? How many people will there be on the planet 100 years
from now? This is of course very hard to tell and it is a research topic on its own.
Recent estimates have suggested an upper bound of about 8-9 billion people. But
let us just pursue our exponential approach a bit further and see what we get. In
Tab le
5.4
below we analyze data in the time period 1990-2000.
Now, the average of the b
n
values is
9
X
1
10
b
D
b
n
D
1:42;
nD0
so
b
100
˛
D
D
0:0142:
Using this growth factor and starting in the year of 2000, we have the model
p
0
.t /
D
0:0142p.t/;
p.0/
D
6:080:
(5.86)
