Based on the information given the average annual income is $19,200.
Using this formula
Estimated average annual income=(Estimated cost+Residual value)/2× Average rate of return
Let plug in the formula
Estimated average annual income=($480,000+$0)/2×8%
Estimated average annual income=$240,000×8%
Estimated average annual income=$19,200
Inconclusion the average annual income is $19,200.
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