Given:
Initial value = $800 per acre
Growth rate = 3% per year
To find:
How long will it be before the land is worth $1000 per acre.
Solution:
The exponential growth model is:
[tex]y=a(1+r)^t[/tex]
Where, y is the new value, a is the initial value, r is the growth rate in decimal and t is the number of years.
Putting [tex]y=1000, a=800, r=0.03[/tex], we get
[tex]1000=800(1+0.03)^t[/tex]
[tex]\dfrac{1000}{800}=(1.03)^t[/tex]
[tex]1.25=(1.03)^t[/tex]
Taking log both sides, we get
[tex]\log 1.25=\log (1.03)^t[/tex]
[tex]0.09691=t\log (1.03)[/tex]
[tex]0.09691=0.012837t[/tex]
Isolating the variable t, we get
[tex]\dfrac{0.09691}{0.012837}=t[/tex]
[tex]7.54927=t[/tex]
[tex]t\approx 7.55[/tex]
Therefore, the land is worth $1000 per acre after 7.55 years.