Answer:
19.25224 mils
Step-by-step explanation:
Property 1 has a total assessed value of ...
$75,000 +125,000 +1,275 = $201,275
and a total tax of
2×$1,937.50 = $3,875
__
Property 2 has a total assessed value of ...
$187,500 +312,500 +3,187.50 = $503,187.50
and a total tax of
2×$4,843.74 = $9,687.48
__
The total assessed value of the two properties is ...
$201,275 +503,187.50 = $704,462.50
The total tax on the two properties is ...
$3,875.00 +9,687.48 = $13,562.48
So, the effective tax rate is ...
$13,562.48/$704,462.50 ≈ 0.01925224 = 19.25224 mils
_____
Additional comments
We have not included penalties in our computation of the effective tax rate, because those can be avoided by timely payment. They are not assessed based on property value, but are based on the time between tax being due and tax being paid. YMMV
We expect the same rate to apply to both parcels. Using this rate for the separate parcels gives values that may be off by a penny. We chose to present the tax rate value to 7 significant figures, because the amount of total tax has 7 significant figures.