Bradford T. answered 12/01/22
Retired Engineer / Upper level math instructor
The problem is asking for the x value when f(x) = avg.
avg = 1.531925
e0.4x = avg
0.4x = ln(avg)
x = 2.5ln(avg)
If you plotted the graph, you can see where f(x) = e0.4x and y= avg intersect.