Answer: $71942.45
We can solve this problem by using the following formula:

To solve for the PVA factor, we will use the formula,

From the given problem, we know that:
r = 4% = 0.04
n = 15
Substituting this to our equation,

Now that we have our PVA factor, we can now solve for the PMT.
We now know that:
PV = $800000
PVA factor = 11.12
Substituting these to the equation:


Hence, the maximum annual withdrawal he can make over the following 15 years is $71942.45