Using an exponential function, it is found that:
a) The doubling time of the salary is of approximately 20 years.
b) The salary will be of $160,000.
An increasing exponential function is modeled by:
[tex]A(t) = A(0)(1 + r)^t[/tex]
In which:
The growth rate for this problem is:
r = 0.035.
The doubling time is t for which A(t) = 2A(0), hence:
[tex]A(t) = A(0)(1 + r)^t[/tex]
[tex]2A(0) = A(0)(1.035)^t[/tex]
[tex](1.035)^t = 2[/tex]
[tex]\log{(1.035)^t} = \log{2}[/tex]
[tex]t\log{1.035} = \log{2}[/tex]
[tex]t = \frac{\log{2}}{\log{1.035}}[/tex]
t = 20 years.
You retire in 40 years, which is 2 doubling periods, hence the salary will be of:
40000 x 2 x 2 = $160,000.
More can be learned about exponential functions at https://brainly.com/question/25537936
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